Add dateTimeConvert scalar function

[Jackie-Jiang]

Add the dateTimeConvert scalar function which is equivalent to the DateTimeConversionTransformFunction so that it can be used for ingestion transform and post aggregation

[codecov-commenter]

Codecov Report

Merging #8292 (556a203) into master (46ed731) will decrease coverage by 1.01%.
The diff coverage is 87.87%.

@@             Coverage Diff              @@
##             master    #8292      +/-   ##
============================================
- Coverage     70.83%   69.81%   -1.02%     
- Complexity     4245     4247       +2     
============================================
  Files          1631     1631              
  Lines         85462    85487      +25     
  Branches      12877    12879       +2     
============================================
- Hits          60539    59687     -852     
- Misses        20746    21663     +917     
+ Partials       4177     4137      -40     

Flag	Coverage Δ
integration1	29.05% <0.00%> (+0.06%)	⬆️
integration2	?
unittests1	66.98% <87.87%> (+0.02%)	⬆️
unittests2	14.20% <0.00%> (+0.03%)	⬆️

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

Impacted Files	Coverage Δ
...inot/common/function/scalar/DateTimeFunctions.java	95.91% <87.87%> (-2.72%)	⬇️
...t/core/plan/StreamingInstanceResponsePlanNode.java	0.00% <0.00%> (-100.00%)	⬇️
...ore/operator/streaming/StreamingResponseUtils.java	0.00% <0.00%> (-100.00%)	⬇️
...ager/realtime/PeerSchemeSplitSegmentCommitter.java	0.00% <0.00%> (-100.00%)	⬇️
...he/pinot/core/plan/StreamingSelectionPlanNode.java	0.00% <0.00%> (-88.89%)	⬇️
...ator/streaming/StreamingSelectionOnlyOperator.java	0.00% <0.00%> (-87.81%)	⬇️
...re/query/reduce/SelectionOnlyStreamingReducer.java	0.00% <0.00%> (-85.72%)	⬇️
...pache/pinot/common/utils/grpc/GrpcQueryClient.java	0.00% <0.00%> (-80.86%)	⬇️
...ller/api/access/BasicAuthAccessControlFactory.java	0.00% <0.00%> (-80.00%)	⬇️
...roker/requesthandler/GrpcBrokerRequestHandler.java	0.00% <0.00%> (-78.58%)	⬇️
... and 83 more

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[xiangfu0]

Please add the PR description