schemadiff: validate uniqueness of CHECK and of FOREIGN KEY constraints

[shlomi-noach]

Description

This PR adds schema-scope validations:

• In the same schema, no two CHECK constraints have the same name.
• In the same schema, no two FOREIGN KEY constraints have the same name.

Note: there is no problem for a CHECK constraint and for a FOREIGN KEY constraint to have the same name.

These validations are compliant with MySQL and are required, as MySQL strictly enforces this uniqueness.

Related Issue(s)

• schemadiff: tracking issue #10203

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
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• Documentation was added or is not required

Deployment Notes

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[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 67.62%. Comparing base (a6c2896) to head (4d5fbd8).
Report is 1 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #17627      +/-   ##
==========================================
- Coverage   67.64%   67.62%   -0.02%     
==========================================
  Files        1586     1586              
  Lines      255629   255647      +18     
==========================================
- Hits       172910   172882      -28     
- Misses      82719    82765      +46     

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