Moving grid summary generation and copying to sts for perf

[aasimkhan30]

Description

Key Changes

1. A lot of code deletions.
2. Deletion of test cases as most of the logic is moved to the backend.
3. Faster summary and copy performance — cell data read is now backend-driven, preventing the extension/VS Code from slowing down due to loading everything in memory on the frontend.

STS PR that moves everything to the backend: microsoft/sqltoolsservice#2520

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Frontend Summary

Screen.Recording.2025-10-06.at.11.08.44.PM.mov

Backend Summary

Screen.Recording.2025-10-06.at.11.05.25.PM.mov

Copy Operation

Not much has changed on the copy side except for adding a loading bar:

Screen.Recording.2025-10-09.at.3.11.16.PM.mov

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Code Changes Checklist

• New or updated unit tests added
• All existing tests pass (npm run test)
• Code follows contributing guidelines
• Telemetry/logging updated if relevant
• No regressions or UX breakage

Reviewers: Please read our reviewer guidelines

[github-actions]

PR Changes

Category	Target Branch	PR Branch	Difference
Code Coverage	56.26%	55.58%	⚪ 0.00%
VSIX Size	4854 KB	4852 KB	⚪ -2 KB ( 0% )
Webview Bundle Size	4012 KB	4004 KB	⚪ -8 KB ( 0% )

[codecov-commenter]

Codecov Report

❌ Patch coverage is 34.66667% with 49 lines in your changes missing coverage. Please review.
✅ Project coverage is 53.70%. Comparing base (c6866eb) to head (f1c22d9).
⚠️ Report is 4 commits behind head on main.

Files with missing lines	Patch %	Lines
src/controllers/queryRunner.ts	2.22%	44 Missing ⚠️
src/queryResult/utils.ts	25.00%	3 Missing ⚠️
src/constants/locConstants.ts	71.42%	2 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #20285      +/-   ##
==========================================
- Coverage   54.40%   53.70%   -0.70%     
==========================================
  Files         198      198              
  Lines       17588    17267     -321     
  Branches     1168     1156      -12     
==========================================
- Hits         9568     9273     -295     
+ Misses       8020     7994      -26     

Files with missing lines	Coverage Δ
src/configurations/config.ts	100.00% <ø> (ø)
src/constants/constants.ts	100.00% <100.00%> (ø)
src/models/contracts/queryExecute.ts	100.00% <100.00%> (ø)
src/models/sqlOutputContentProvider.ts	28.02% <ø> (+0.16%)	⬆️
src/sharedInterfaces/queryResult.ts	100.00% <ø> (ø)
src/constants/locConstants.ts	80.78% <71.42%> (-0.01%)	⬇️
src/queryResult/utils.ts	51.66% <25.00%> (+8.08%)	⬆️
src/controllers/queryRunner.ts	44.81% <2.22%> (-24.39%)	⬇️

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