Update transforms documentation

[trbromley]

Description of the Change:

• qml.transforms.core.transform is now top level qml.transform
• Update qml.transforms page
• Update the documentation for qml.transforms.core.transform
• Update thar args and returns of all transform using qml.transforms.core.transform

[github-actions]

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Please edit doc/releases/changelog-dev.md with:

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[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (5cd8354) 99.64% compared to head (c411ca5) 99.64%.
Report is 4 commits behind head on 0.33-doc-fixes.

Additional details and impacted files

@@                Coverage Diff                 @@
##           0.33-doc-fixes    #4682      +/-   ##
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- Coverage           99.64%   99.64%   -0.01%     
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  Files                 380      380              
  Lines               34245    34000     -245     
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- Hits                34124    33878     -246     
- Misses                121      122       +1     

Files	Coverage Δ
pennylane/__init__.py	100.00% <ø> (ø)
pennylane/devices/device_api.py	98.57% <ø> (-0.03%)	⬇️
pennylane/devices/preprocess.py	100.00% <100.00%> (ø)
pennylane/fourier/circuit_spectrum.py	100.00% <100.00%> (ø)
pennylane/gradients/__init__.py	100.00% <ø> (ø)
pennylane/gradients/finite_difference.py	100.00% <100.00%> (ø)
pennylane/gradients/hadamard_gradient.py	100.00% <100.00%> (ø)
pennylane/gradients/parameter_shift.py	100.00% <100.00%> (ø)
pennylane/gradients/parameter_shift_cv.py	99.62% <100.00%> (ø)
pennylane/gradients/parameter_shift_hessian.py	100.00% <ø> (ø)
... and 43 more

... and 39 files with indirect coverage changes

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[timmysilv]

nothing more from me, thanks for getting through all of this!

[trbromley]

Thanks @rmoyard! I still need to look through transform, transform_dispatcher and transform_program (will do that this afternoon).

For now I'll leave my comments from looking through carefully at the transform docs.

My main nontrivial comments are around some replication of the examples - happy to discuss this.

Thanks again for this effort!

[rmoyard]

💯