BinlogEvent: publish ServerID() function

[shlomi-noach]

Description

MySQL binlog protocol: for completeness and consistency, we add the ServerID() function in BinlogEvent. The function is already implemented and tested in the implementing binlogEvent type, but was never made public in the interface.

Related Issue(s)

none

Checklist

• "Backport to:" labels have been added if this change should be back-ported to release branches
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• Tests were added or are not required
• Did the new or modified tests pass consistently locally and on CI?
• Documentation was added or is not required

Deployment Notes

[vitess-bot]

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[codecov]

Codecov Report

Attention: Patch coverage is 0% with 2 lines in your changes missing coverage. Please review.

Project coverage is 68.95%. Comparing base (a513601) to head (d2dba1d).
Report is 14 commits behind head on main.

Files with missing lines	Patch %	Lines
go/mysql/binlog_event_filepos.go	0.00%	2 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #16713      +/-   ##
==========================================
+ Coverage   68.93%   68.95%   +0.01%     
==========================================
  Files        1565     1565              
  Lines      201745   201747       +2     
==========================================
+ Hits       139075   139105      +30     
+ Misses      62670    62642      -28     

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