refactor(amazonq): split CodeWhispererService into multiple files

[liramon1]

Problem

The CodeWhispererService base, IAM, and token variants are all in the same file. This makes it cumbersome to extend as more features are added.

Solution

This is part of #1981.

Split the CodeWhispererService class into their own files and update the import paths for them.

License

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 54.15020% with 1160 lines in your changes missing coverage. Please review.

Project coverage is 61.15%. Comparing base (1491f4f) to head (d41f3a3).

Files with missing lines	Patch %	Lines
.../language-server/agenticChat/tools/mcp/mcpUtils.ts	39.81%	328 Missing ⚠️
...anguage-server/agenticChat/tools/mcp/mcpManager.ts	62.84%	149 Missing ⚠️
...ge-server/agenticChat/tools/mcp/mcpEventHandler.ts	18.46%	106 Missing ⚠️
chat-client/src/client/mynahUi.ts	30.15%	86 Missing and 2 partials ⚠️
.../language-server/agenticChat/tools/mcp/mcpTypes.ts	22.50%	62 Missing ⚠️
...orkspaceContext/dependency/dependencyDiscoverer.ts	2.43%	40 Missing ⚠️
server/aws-lsp-codewhisperer/src/shared/utils.ts	9.09%	40 Missing ⚠️
...anguage-server/workspaceContext/artifactManager.ts	11.62%	38 Missing ⚠️
...nguage-server/agenticChat/agenticChatController.ts	71.05%	33 Missing ⚠️
...rver/agenticChat/tools/qCodeAnalysis/codeReview.ts	86.32%	29 Missing ⚠️
... and 24 more

Additional details and impacted files

@@                    Coverage Diff                     @@
##           feature/flare-iam-base    #1974      +/-   ##
==========================================================
- Coverage                   65.96%   61.15%   -4.82%     
==========================================================
  Files                         238      240       +2     
  Lines                       50623    52029    +1406     
  Branches                     3385     3104     -281     
==========================================================
- Hits                        33393    31816    -1577     
- Misses                      17170    20157    +2987     
+ Partials                       60       56       -4     

Flag	Coverage Δ
unittests	61.15% <54.15%> (-4.82%)	⬇️

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