Add MySQL tlog tiles API integration test

[roger2hk]

#8 #21

This PR not only add the MySQL tlog tiles API integration test but also fixes the read entry bundle API bug in example-mysql.

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 0% with 1 line in your changes missing coverage. Please review.

Project coverage is 34.92%. Comparing base (46ec9c2) to head (24f1e9e).
Report is 48 commits behind head on main.

Files	Patch %	Lines
cmd/example-mysql/main.go	0.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #128      +/-   ##
==========================================
- Coverage   35.80%   34.92%   -0.89%     
==========================================
  Files          16       33      +17     
  Lines        1363     2772    +1409     
==========================================
+ Hits          488      968     +480     
- Misses        801     1696     +895     
- Partials       74      108      +34     

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[roger2hk]

Some refactoring TODOs in my mind:

• Apply the same integration test to GCP
  • Move integration_test.go from integration/example-mysql/ to integration/
  • Add new job gcp-tlog-tiles-api to .github/workflows/integration_test.yml
• Add CheckInclusionProof in tlog tiles client.
• Add write API in tlog tiles client. (Possibily move the one from hammer?)