add scalar function support for AT TIME ZONE

[agavra]

depends on #9477 to run the custom syntax - this PR adds the functionality to execute the AT TIME ZONE method and was tested using my local time zone as well as -Duser.timezone=GMT.

[codecov-commenter]

Codecov Report

Merging #9480 (9ac6b09) into master (3057712) will increase coverage by 1.24%. The diff coverage is 90.90%.

@@             Coverage Diff              @@
##             master    #9480      +/-   ##
============================================
+ Coverage     68.66%   69.90%   +1.24%     
- Complexity     5136     5194      +58     
============================================
  Files          1916     1917       +1     
  Lines        102069   102208     +139     
  Branches      15481    15510      +29     
============================================
+ Hits          70083    71447    +1364     
+ Misses        26980    25715    -1265     
- Partials       5006     5046      +40     

Flag	Coverage Δ
integration1	25.95% <0.00%> (-0.18%)	:arrow_down:
integration2	24.82% <0.00%> (?)
unittests1	67.16% <90.90%> (+0.04%)	:arrow_up:
unittests2	15.52% <18.18%> (+<0.01%)	:arrow_up:

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

Impacted Files	Coverage Δ
...apache/pinot/common/function/FunctionRegistry.java	84.61% <0.00%> (-2.23%)	:arrow_down:
...inot/common/function/scalar/DateTimeFunctions.java	96.47% <100.00%> (+0.22%)	:arrow_up:
...apache/pinot/sql/parsers/parser/SqlAtTimeZone.java	100.00% <100.00%> (+7.69%)	:arrow_up:
.../java/org/apache/pinot/query/QueryEnvironment.java	84.12% <100.00%> (+0.25%)	:arrow_up:
...ntroller/helix/core/minion/TaskMetricsEmitter.java	34.88% <0.00%> (-51.17%)	:arrow_down:
...perator/filter/SortedIndexBasedFilterOperator.java	85.71% <0.00%> (-7.62%)	:arrow_down:
...tream/kafka20/server/KafkaDataServerStartable.java	72.91% <0.00%> (-6.25%)	:arrow_down:
.../helix/core/minion/MinionInstancesCleanupTask.java	77.27% <0.00%> (-4.55%)	:arrow_down:
.../impl/dictionary/BaseOffHeapMutableDictionary.java	81.33% <0.00%> (-3.34%)	:arrow_down:
...gregation/function/StUnionAggregationFunction.java	73.52% <0.00%> (-2.95%)	:arrow_down:
... and 155 more

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[agavra]

Converting to draft until #9546 is supported