Add support for Update Multi Table

[harshit-gangal]

Description

This PR adds support for update statements with multi-table references.

Related Issue(s)

• Closes Feature Request: Support for Update with multi table reference #15214

Checklist

• 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]

Review Checklist

Hello reviewers! 👋 Please follow this checklist when reviewing this Pull Request.

General

• Ensure that the Pull Request has a descriptive title.
• Ensure there is a link to an issue (except for internal cleanup and flaky test fixes), new features should have an RFC that documents use cases and test cases.

Tests

• Bug fixes should have at least one unit or end-to-end test, enhancement and new features should have a sufficient number of tests.

Documentation

• Apply the release notes (needs details) label if users need to know about this change.
• New features should be documented.
• There should be some code comments as to why things are implemented the way they are.
• There should be a comment at the top of each new or modified test to explain what the test does.

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Backward compatibility

• Protobuf changes should be wire-compatible.
• Changes to _vt tables and RPCs need to be backward compatible.
• RPC changes should be compatible with vitess-operator
• If a flag is removed, then it should also be removed from vitess-operator and arewefastyet, if used there.
• vtctl command output order should be stable and awk-able.

[codecov]

Codecov Report

Attention: 32 lines in your changes are missing coverage. Please review.

Comparison is base (14473b9) 67.34% compared to head (3d456e8) 67.43%.
Report is 5 commits behind head on main.

❗ Current head 3d456e8 differs from pull request most recent head a52c54a. Consider uploading reports for the commit a52c54a to get more accurate results

Files	Patch %	Lines
go/vt/sqlparser/ast_funcs.go	54.83%	28 Missing ⚠️
go/vt/vtgate/planbuilder/operators/SQL_builder.go	96.22%	2 Missing ⚠️
go/vt/vtgate/planbuilder/operators/update.go	92.00%	2 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #15211      +/-   ##
==========================================
+ Coverage   67.34%   67.43%   +0.08%     
==========================================
  Files        1560     1560              
  Lines      192571   192807     +236     
==========================================
+ Hits       129695   130011     +316     
+ Misses      62876    62796      -80     

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