Added query for initialized extensions

[mloufra]

Signed-off-by: Frank Lou mloufra@amazon.com

Description

Create a feature to have an extension query to OpenSearch to obtain a list of initialized extensions and determine whether a particular extension is initialized.
Equivalent PR on OpenSearch : opensearch-project/OpenSearch#5628 opensearch-project/OpenSearch#5658

Issues Resolved

fixes #149

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[dbwiddis]

LGTM (pending merge of #5658 and passing tests)

[owaiskazi19]

Run spotless to fix the build errors:

> Task :spotlessJava
FAILURE: Build failed with an exception.
> Task :spotlessJavaCheck FAILED

[codecov-commenter]

Codecov Report

Merging #300 (fff3446) into main (4555529) will decrease coverage by 3.56%.
The diff coverage is 0.00%.

@@             Coverage Diff              @@
##               main     #300      +/-   ##
============================================
- Coverage     73.22%   69.66%   -3.57%     
  Complexity      117      117              
============================================
  Files            25       26       +1     
  Lines           508      534      +26     
  Branches         15       15              
============================================
  Hits            372      372              
- Misses          128      154      +26     
  Partials          8        8              

Impacted Files	Coverage Δ
...main/java/org/opensearch/sdk/ExtensionsRunner.java	65.77% <0.00%> (-4.74%)	⬇️
...k/handlers/ExtensionDependencyResponseHandler.java	0.00% <0.00%> (ø)

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