DRAFT: Adding SHOW TABLES/DESCRIBE table support

[aadilkhalifa]

PR to add support for "SHOW TABLES" and "DESCRIBE table" queries.

Current status:

• [x] SHOW TABLES
• [x] DESCRIBE table

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 2.72727% with 107 lines in your changes missing coverage. Please review.

Project coverage is 63.97%. Comparing base (59551e4) to head (86dab1d). Report is 1497 commits behind head on master.

Files with missing lines	Patch %	Lines
...sthandler/BaseSingleStageBrokerRequestHandler.java	0.00%	63 Missing and 2 partials :warning:
...t/controller/api/resources/PinotQueryResource.java	8.57%	29 Missing and 3 partials :warning:
...apache/pinot/sql/parsers/parser/SqlShowTables.java	0.00%	8 Missing :warning:
...org/apache/pinot/sql/parsers/CalciteSqlParser.java	0.00%	1 Missing and 1 partial :warning:

Additional details and impacted files

@@             Coverage Diff              @@
##             master   #12537      +/-   ##
============================================
+ Coverage     61.75%   63.97%   +2.22%     
- Complexity      207     1608    +1401     
============================================
  Files          2436     2707     +271     
  Lines        133233   149321   +16088     
  Branches      20636    22887    +2251     
============================================
+ Hits          82274    95530   +13256     
- Misses        44911    46770    +1859     
- Partials       6048     7021     +973     

Flag	Coverage Δ
custom-integration1	100.00% <ø> (+99.99%)	:arrow_up:
integration	100.00% <ø> (+99.99%)	:arrow_up:
integration1	100.00% <ø> (+99.99%)	:arrow_up:
integration2	0.00% <ø> (ø)
java-11	63.96% <2.72%> (+2.25%)	:arrow_up:
java-21	63.84% <2.72%> (+2.21%)	:arrow_up:
skip-bytebuffers-false	63.97% <2.72%> (+2.22%)	:arrow_up:
skip-bytebuffers-true	63.82% <2.72%> (+36.09%)	:arrow_up:
temurin	63.97% <2.72%> (+2.22%)	:arrow_up:
unittests	63.97% <2.72%> (+2.22%)	:arrow_up:
unittests1	56.31% <0.00%> (+9.42%)	:arrow_up:
unittests2	34.42% <2.72%> (+6.69%)	:arrow_up:

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