Add FieldCapabilities overloads without a body

This commit introduces overloads of field_caps API
that do not take a body, as a BWC change for body introduced in
elastic/elasticsearch#57276

(cherry picked from commit 1f02223)

src/Elasticsearch.Net/Patch.ElasticLowLevelClient.cs

@@ -0,0 +1,33 @@
+// Licensed to Elasticsearch B.V under one or more agreements.
+// Elasticsearch B.V licenses this file to you under the Apache 2.0 License.
+// See the LICENSE file in the project root for more information
+
+using System.Threading;
+using System.Threading.Tasks;
+using static Elasticsearch.Net.HttpMethod;
+
+namespace Elasticsearch.Net
+{
+	// Introduced for BWC for body introduced in https://github.com/elastic/elasticsearch/pull/57276
+	public partial class ElasticLowLevelClient
+	{
+		///<summary>POST on /_field_caps <para>https://www.elastic.co/guide/en/elasticsearch/reference/master/search-field-caps.html</para></summary>
+		///<param name = "requestParameters">Request specific configuration such as querystring parameters &amp; request specific connection settings.</param>
+		public TResponse FieldCapabilities<TResponse>(FieldCapabilitiesRequestParameters requestParameters = null)
+			where TResponse : class, IElasticsearchResponse, new() => DoRequest<TResponse>(POST, "_field_caps", null, RequestParams(requestParameters));
+		///<summary>POST on /_field_caps <para>https://www.elastic.co/guide/en/elasticsearch/reference/master/search-field-caps.html</para></summary>
+		///<param name = "requestParameters">Request specific configuration such as querystring parameters &amp; request specific connection settings.</param>
+		public Task<TResponse> FieldCapabilitiesAsync<TResponse>(FieldCapabilitiesRequestParameters requestParameters = null, CancellationToken ctx = default)
+			where TResponse : class, IElasticsearchResponse, new() => DoRequestAsync<TResponse>(POST, "_field_caps", ctx, null, RequestParams(requestParameters));
+		///<summary>POST on /{index}/_field_caps <para>https://www.elastic.co/guide/en/elasticsearch/reference/master/search-field-caps.html</para></summary>
+		///<param name = "index">A comma-separated list of index names; use the special string `_all` or Indices.All to perform the operation on all indices</param>
+		///<param name = "requestParameters">Request specific configuration such as querystring parameters &amp; request specific connection settings.</param>
+		public TResponse FieldCapabilities<TResponse>(string index, FieldCapabilitiesRequestParameters requestParameters = null)
+			where TResponse : class, IElasticsearchResponse, new() => DoRequest<TResponse>(POST, Url($"{index:index}/_field_caps"), null, RequestParams(requestParameters));
+		///<summary>POST on /{index}/_field_caps <para>https://www.elastic.co/guide/en/elasticsearch/reference/master/search-field-caps.html</para></summary>
+		///<param name = "index">A comma-separated list of index names; use the special string `_all` or Indices.All to perform the operation on all indices</param>
+		///<param name = "requestParameters">Request specific configuration such as querystring parameters &amp; request specific connection settings.</param>
+		public Task<TResponse> FieldCapabilitiesAsync<TResponse>(string index, FieldCapabilitiesRequestParameters requestParameters = null, CancellationToken ctx = default)
+			where TResponse : class, IElasticsearchResponse, new() => DoRequestAsync<TResponse>(POST, Url($"{index:index}/_field_caps"), ctx, null, RequestParams(requestParameters));
+	}
+}

src/Elasticsearch.Net/Patch.IElasticLowLevelClient.cs

@@ -0,0 +1,32 @@
+// Licensed to Elasticsearch B.V under one or more agreements.
+// Elasticsearch B.V licenses this file to you under the Apache 2.0 License.
+// See the LICENSE file in the project root for more information
+
+using System.Threading;
+using System.Threading.Tasks;
+
+namespace Elasticsearch.Net
+{
+	// Introduced for BWC for body introduced in https://github.com/elastic/elasticsearch/pull/57276
+	public partial interface IElasticLowLevelClient
+	{
+		///<summary>POST on /_field_caps <para>https://www.elastic.co/guide/en/elasticsearch/reference/master/search-field-caps.html</para></summary>
+		///<param name = "requestParameters">Request specific configuration such as querystring parameters &amp; request specific connection settings.</param>
+		public TResponse FieldCapabilities<TResponse>(FieldCapabilitiesRequestParameters requestParameters = null)
+			where TResponse : class, IElasticsearchResponse, new();
+		///<summary>POST on /_field_caps <para>https://www.elastic.co/guide/en/elasticsearch/reference/master/search-field-caps.html</para></summary>
+		///<param name = "requestParameters">Request specific configuration such as querystring parameters &amp; request specific connection settings.</param>
+		public Task<TResponse> FieldCapabilitiesAsync<TResponse>(FieldCapabilitiesRequestParameters requestParameters = null, CancellationToken ctx = default)
+			where TResponse : class, IElasticsearchResponse, new();
+		///<summary>POST on /{index}/_field_caps <para>https://www.elastic.co/guide/en/elasticsearch/reference/master/search-field-caps.html</para></summary>
+		///<param name = "index">A comma-separated list of index names; use the special string `_all` or Indices.All to perform the operation on all indices</param>
+		///<param name = "requestParameters">Request specific configuration such as querystring parameters &amp; request specific connection settings.</param>
+		public TResponse FieldCapabilities<TResponse>(string index, FieldCapabilitiesRequestParameters requestParameters = null)
+			where TResponse : class, IElasticsearchResponse, new();
+		///<summary>POST on /{index}/_field_caps <para>https://www.elastic.co/guide/en/elasticsearch/reference/master/search-field-caps.html</para></summary>
+		///<param name = "index">A comma-separated list of index names; use the special string `_all` or Indices.All to perform the operation on all indices</param>
+		///<param name = "requestParameters">Request specific configuration such as querystring parameters &amp; request specific connection settings.</param>
+		public Task<TResponse> FieldCapabilitiesAsync<TResponse>(string index, FieldCapabilitiesRequestParameters requestParameters = null, CancellationToken ctx = default)
+			where TResponse : class, IElasticsearchResponse, new();
+	}
+}