parser: Support literal in default value as function

[morgo]

What problem does this PR solve?

Issue Number: ref #54700

TiDB does not correctly support "default value as expression", but rather supports closer to "default value as function". To support arbitrary expressions is more complicated, since some have to be restricted.

What this does is relaxes the handling so as well as functions, literals are also supported. Full expressions are not.

It does not close the referenced issue.

Problem Summary:

What changed and how does it work?

The parser is changed and an integration test is added.

Check List

Tests

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

  • I checked and no code files have been changed.

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]

[APPROVALNOTIFIER] This PR is NOT APPROVED

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[tiprow]

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[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 74.8567%. Comparing base (7cdf918) to head (a03666f).
Report is 309 commits behind head on master.

Additional details and impacted files

@@               Coverage Diff                @@
##             master     #54706        +/-   ##
================================================
+ Coverage   72.8418%   74.8567%   +2.0148%     
================================================
  Files          1560       1569         +9     
  Lines        438616     453795     +15179     
================================================
+ Hits         319496     339696     +20200     
+ Misses        99538      93249      -6289     
- Partials      19582      20850      +1268     

Flag	Coverage Δ
integration	49.5132% <ø> (?)
unit	71.6366% <ø> (-0.2087%)	⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.

Components	Coverage Δ
dumpling	52.9567% <ø> (ø)
parser	∅ <ø> (∅)
br	52.4960% <ø> (+6.6170%)	⬆️

[ti-chi-bot]

PR needs rebase.

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