tools: gmail

[mtanzim]

This PR introduces a new tool for searching Google Mail.

Code Changes:

• New files added: gmail_test/main.py, src/backend/tools/google_mail/__init__.py, src/backend/tools/google_mail/auth.py, src/backend/tools/google_mail/constants.py, and src/backend/tools/google_mail/tool.py.
• In src/backend/config/tools.py, the GoogleMail and GoogleMailAuth classes are imported, and Google_Mail is added to the ToolName enum.
• In src/backend/tools/__init__.py, the GoogleMail and GoogleMailAuth classes are imported.
• In src/backend/tools/google_mail/__init__.py, the GoogleMail, GoogleMailAuth, and GOOGLE_MAIL_TOOL_ID constants are imported.
• In .gitignore, credentials.json and token.json are added to the list of ignored files.

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 52.17391% with 66 lines in your changes missing coverage. Please review.

Project coverage is 75.94%. Comparing base (6e7f791) to head (4e01747).
Report is 79 commits behind head on main.

Files with missing lines	Patch %	Lines
src/backend/tools/google_mail/auth.py	43.85%	32 Missing ⚠️
src/backend/tools/google_mail/tool.py	40.81%	29 Missing ⚠️
src/backend/services/compass.py	37.50%	5 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #655      +/-   ##
==========================================
- Coverage   77.10%   75.94%   -1.16%     
==========================================
  Files         238      242       +4     
  Lines       10455    10727     +272     
==========================================
+ Hits         8061     8147      +86     
- Misses       2394     2580     +186     

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[tianjing-li]

Closing