executor, infoschema: Add foreign key constraint to infoschema.table_constraints

[espresso98]

What problem does this PR solve?

Issue Number: close #28918

Problem Summary:

This adds foreign key constraints to the infoschema table table_constraints. The output is MySQL compatible.

What is changed and how it works?

This adds foreign key constraints to the infoschema table table_constraints. The output is MySQL compatible.

Check List

Tests

• Unit test
• Integration test
• Manual test (add detailed scripts or steps below)
• No code

Side effects

• Performance regression: Consumes more CPU
• Performance regression: Consumes more Memory
• Breaking backward compatibility

Documentation

• Affects user behaviors
• Contains syntax changes
• Contains variable changes
• Contains experimental features
• Changes MySQL compatibility
  It improves compatibility

Release note

 The infoschema table `table_constraints` now includes the output of foreign key constraints. Please note  FOREIGN KEY constraints are not still enforced by TiDB. 

[ti-chi-bot]

[REVIEW NOTIFICATION]

This pull request has been approved by:

• Defined2014
• morgo

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[espresso98]

/cc @morgo

[sre-bot]

Code Coverage Details: https://codecov.io/github/pingcap/tidb/commit/d4c701728956b3b8d48e45a2faadc1f9da8936ce

[morgo]

/check-issue-triage-complete

[morgo]

/check-issue-triage-complete

[morgo]

LGTM

[morgo]

/run-unit-test

[hawkingrei]

/run-unit-test

[Defined2014]

/run-mysql-test

[Defined2014]

/run-mysql-test

[Defined2014]

/merge

[ti-chi-bot]

This pull request has been accepted and is ready to merge.

Commit hash: 88708af

[hawkingrei]

/run-unit-test

[hawkingrei]

/run-check_title

[ti-chi-bot]

@espresso98: Your PR was out of date, I have automatically updated it for you.

At the same time I will also trigger all tests for you:

/run-all-tests

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