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 :warning:

Additional details and impacted files

```diff @@ 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?)