Minor: Generate the supported Spark builtin expression list into MD file

[comphead]

Which issue does this PR close?

Follow up on #331 Closes #282 Related #240

Rationale for this change

Generate the supported Spark builtin expression list into MD file instead of txt file. Txt file still exists as it provides the reason why some expression is not supported

What changes are included in this PR?

How are these changes tested?

[andygrove]

This is very cool @comphead but it looks like it is not detecting any of the aggregate functions that we support?

[comphead]

@andygrove @advancedxy I fixed the test, implementing extra parsing and manual small tests if the parsing is complicated. I hope now we have better picture.

[comphead]

Thanks @advancedxy I fixed the flaws you mentioned. However I'd like to make refactoring you recommended in followup PR, this PR getting too large for review

[advancedxy]

Thanks @advancedxy I fixed the flaws you mentioned. However I'd like to make refactoring you recommended in followup PR, this PR getting too large for review

Of course, sounds good to me.

[comphead]

@andygrove I fixed all the comments, however you are right, sometimes we support partially the function. means part of syntax or some value range not supported.

here comes an idea for follow up PR to introduce partially supported status(or similar) with the reason why it is supported partially

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 34.23%. Comparing base (9ca63a2) to head (e8f3b77). Report is 27 commits behind head on main.

Additional details and impacted files

@@             Coverage Diff              @@
##               main     #455      +/-   ##
============================================
+ Coverage     34.18%   34.23%   +0.04%     
+ Complexity      851      806      -45     
============================================
  Files           116      105      -11     
  Lines         38570    38488      -82     
  Branches       8531     8562      +31     
============================================
- Hits          13187    13175      -12     
+ Misses        22612    22554      -58     
+ Partials       2771     2759      -12     

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