*: add tidb_row_checksum() as a builtin function

[zyguan]

What problem does this PR solve?

Issue Number: ref #42747

Problem Summary: as decribed in #42747, we need to implement a builtin function tidb_row_checksum to export row checksums to users.

What is changed and how it works?

This is a quick & dirty implementation of tidb_row_checksum, which can only be used as a select field in a fast point plan. tidb_row_checksum() will be rewritten as a dummy column when buildSchemaFromFields in TryFastPlan and ChunkDecoder will fill this dummy column with row checksum info.

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

Release note

Please refer to Release Notes Language Style Guide to write a quality release note.

None

[ti-chi-bot]

[REVIEW NOTIFICATION]

This pull request has been approved by:

• 3AceShowHand
• cfzjywxk

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[cfzjywxk]

LGTM

[zyguan]

/merge

[ti-chi-bot]

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

Commit hash: b816ecc

[zyguan]

/cherry-pick release-7.1

[ti-chi-bot]

@zyguan: new pull request created to branch release-7.1: #43634.

In response to this:

/cherry-pick release-7.1

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