Make MLStyle.jl & MacroTools.jl development-time only dependencies

[thautwarm]

Basically it includes DevOnly.jl and achieves the functionality via loaded expanded ASTs.

[codecov-commenter]

Codecov Report

Merging #83 (8c3a367) into main (8ec802c) will decrease coverage by 7.74%.
The diff coverage is 4.91%.

❗ Your organization needs to install the Codecov GitHub app to enable full functionality.

@@            Coverage Diff             @@
##             main      #83      +/-   ##
==========================================
- Coverage   65.53%   57.80%   -7.74%     
==========================================
  Files          12       14       +2     
  Lines         946      974      +28     
==========================================
- Hits          620      563      -57     
- Misses        326      411      +85     

Files	Coverage Δ
TyPython/src/CPython.NumPy.jl	92.85% <ø> (-0.17%)	⬇️
TyPython/src/CPython.jl	72.72% <ø> (ø)
TyPython/src/TyPython.jl	100.00% <ø> (ø)
TyPython/src/Utils.jl	63.63% <ø> (+3.63%)	⬆️
TyPython/src/CPython.Dev.jl	57.33% <0.00%> (-6.21%)	⬇️
TyPython/src/DevOnly.jl	29.16% <29.16%> (ø)
TyPython/src/CPython.NumPy.DevOnly.jl	0.00% <0.00%> (ø)
TyPython/src/Reflection.DevOnly.jl	0.00% <0.00%> (ø)