feat: add QueryContext for AT mode

[simple-xair]

• I have registered the PR changes.

What this PR does:

Which issue(s) this PR fixes:

Fixes #1038

Special notes for your reviewer:

Does this PR introduce a user-facing change?:

[LucienShen-Liu]

Hi, when you have time, please fix the CI (build and codecov / build (1.2) (pull_request)). The integration tests are currently having issues, but they should be able to pass once we fix them.

[codecov-commenter]

Codecov Report

❌ Patch coverage is 40.78947% with 45 lines in your changes missing coverage. Please review.
✅ Project coverage is 56.45%. Comparing base (b18bcb0) to head (b33e333).

Files with missing lines	Patch %	Lines
pkg/datasource/sql/conn_at.go	8.88%	39 Missing and 2 partials ⚠️
pkg/datasource/sql/conn.go	0.00%	2 Missing ⚠️
.../datasource/sql/exec/select_for_update_executor.go	0.00%	2 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #1039      +/-   ##
==========================================
- Coverage   56.49%   56.45%   -0.04%     
==========================================
  Files         266      267       +1     
  Lines       17484    17545      +61     
==========================================
+ Hits         9877     9905      +28     
- Misses       6772     6804      +32     
- Partials      835      836       +1     

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