Align TdsExecuteRPC between netcore and netfx

[MichelZ]

Splitting up TdsExecuteRPC to multiple functions to align netcore and netfx

Part of #2953

[codecov]

Codecov Report

Attention: Patch coverage is 81.59204% with 37 lines in your changes missing coverage. Please review.

Project coverage is 72.46%. Comparing base (4bc9ee6) to head (ed8552b).
Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
...nt/netfx/src/Microsoft/Data/SqlClient/TdsParser.cs	81.40%	37 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #2985      +/-   ##
==========================================
- Coverage   72.50%   72.46%   -0.04%     
==========================================
  Files         288      288              
  Lines       59529    59548      +19     
==========================================
- Hits        43159    43150       -9     
- Misses      16370    16398      +28     

Flag	Coverage Δ
addons	92.58% <ø> (ø)
netcore	75.37% <100.00%> (-0.07%)	⬇️
netfx	70.93% <81.40%> (+<0.01%)	⬆️

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