feat: implement_comet_native_lpad_expr

[coderfender]

Which issue does this PR close?

Closes #2101

Closes #.

Rationale for this change

Moving towards goal to support more native operations and not fallback to spark .

What changes are included in this PR?

How are these changes tested?

Unit tests in comet expression suite

If tests are not included in your PR, please explain why (for example, are they covered by existing tests)?
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[comphead]

Thanks @coderfender This function might be a good candidate for https://github.com/apache/datafusion/tree/main/datafusion/spark/src/function

[coderfender]

@mbutrovich , Once the PR #2099 is merged, I plan to change code in this branch to leverage the same class since most of the code for rpad could be leveraged to support lpad operation as well

[coderfender]

@comphead , @mbutrovich I leveraged #2099 to implement lpad expression in the same class given the high similarity among the expressions. Please take a look whenever you get a chance .
Thank you

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 58.56%. Comparing base (f09f8af) to head (40cb4fe).
⚠️ Report is 565 commits behind head on main.

Additional details and impacted files

@@             Coverage Diff              @@
##               main    #2102      +/-   ##
============================================
+ Coverage     56.12%   58.56%   +2.43%     
- Complexity      976     1445     +469     
============================================
  Files           119      146      +27     
  Lines         11743    13541    +1798     
  Branches       2251     2356     +105     
============================================
+ Hits           6591     7930    +1339     
- Misses         4012     4379     +367     
- Partials       1140     1232      +92     

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[comphead]

Thanks @coderfender please add also tests from
https://spark.apache.org/docs/latest/api/sql/#lpad

[coderfender]

Thank you @comphead , It seems like the tests mentioned are adding non space chars while we still only support spaces (which will be fixed with #2436 ). Do you think it is a good idea to hold on to this PR until #2436 is closed ?

[coderfender]

@comphead Changes are ready for review (please rerun the failed test caused due to a transient error)

[comphead]

THanks @coderfender I think we very close

[coderfender]

Thank you @comphead . Let me push fixes right away and re run CI

[coderfender]

@comphead thank you for kicking off the CI . Please review the changes whenever you get a chance
Thank you

[comphead]

Thanks @coderfender I think this PR is good to go

[coderfender]

Thank you very much for the swift approval @comphead

[coderfender]

I will raise a doc change PR shortly