Separate out RequestOptions from RequestContext

[annelo-msft]

This is so RequestOptions can be used by Gen 1 Generated Clients and not have ambiguity in the method signature regarding which CancellationToken takes precedence, whether two CTs are joined, etc.

Fixes Azure/autorest.csharp#1666

[azure-sdk]

API changes have been detected in Azure.Core. You can review API changes here

[pakrym]

@KrzysztofCwalina @tg-msft I feel that confusion created by having two very similar "context" types is way larger than confusion created by having 2 places to set cancellation tokens.

I prefer option 3 from Azure/azure-sdk#3391. It doesn't require a new type just to solve a few corner cases.

[azure-sdk]

API changes have been detected in Azure.Core. You can review API changes here

API changes

+     public class RequestOptions {
+         public RequestOptions();
+         public ErrorOptions ErrorOptions { get; set; }
+         public void AddPolicy(HttpPipelinePolicy policy, HttpPipelinePosition position);
+     }
-     public class RequestContext {
+     public class RequestContext : RequestOptions {
-         public ErrorOptions ErrorOptions { get; set; }
-         public void AddPolicy(HttpPipelinePolicy policy, HttpPipelinePosition position);

[azure-sdk]

API changes have been detected in Azure.Core. You can review API changes here

API changes

+     public class RequestOptions {
+         public RequestOptions();
+         public ErrorOptions ErrorOptions { get; set; }
+         public void AddPolicy(HttpPipelinePolicy policy, HttpPipelinePosition position);
+     }
-     public class RequestContext {
+     public class RequestContext : RequestOptions {
-         public ErrorOptions ErrorOptions { get; set; }
-         public void AddPolicy(HttpPipelinePolicy policy, HttpPipelinePosition position);

[annelo-msft]

We will introduce RequestOptions in Core.Experimental to work out details around the use of RO in HLC APIs prior to putting it into Core.

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[annelo-msft]

Closing in favor of: #27149