Rename the pennylane/measure.py file to pennylane/measurements.py

[antalszava]

Context:
In preparations to introduce the user interface for mid-circuit measurements (see #2211), we'd like to allow qml.measure to be an accessible name.

Description of the Change:

Carries out the pennylane/measure.py -> pennylane/measurements.py renaming.

Benefits:

qml.measure will be a vacant name to use and no conflicts arise.

Possible Drawbacks:

Minor: plugins or demos might be dependent on the renaming, however, no such occurrences have been found so far.

Related GitHub Issues:
N/A

[github-actions]

Hello. You may have forgotten to update the changelog!
Please edit doc/releases/changelog-dev.md with:

• A one-to-two sentence description of the change. You may include a small working example for new features.
• A link back to this PR.
• Your name (or GitHub username) in the contributors section.

[codecov]

Codecov Report

Merging #2236 (19bb467) into master (5a6c2f5) will increase coverage by 0.05%.
The diff coverage is 100.00%.

❗ Current head 19bb467 differs from pull request most recent head 53abc95. Consider uploading reports for the commit 53abc95 to get more accurate results

@@            Coverage Diff             @@
##           master    #2236      +/-   ##
==========================================
+ Coverage   99.21%   99.27%   +0.05%     
==========================================
  Files         232      231       -1     
  Lines       18559    18379     -180     
==========================================
- Hits        18413    18245     -168     
+ Misses        146      134      -12     

Impacted Files	Coverage Δ
pennylane/measurements.py	99.07% <ø> (ø)
pennylane/transforms/hamiltonian_expand.py	100.00% <ø> (ø)
pennylane/__init__.py	100.00% <100.00%> (ø)
pennylane/_device.py	97.98% <100.00%> (+0.01%)	⬆️
pennylane/_qubit_device.py	98.72% <100.00%> (+<0.01%)	⬆️
pennylane/circuit_graph.py	95.00% <100.00%> (+0.53%)	⬆️
pennylane/drawer/representation_resolver.py	99.43% <100.00%> (+<0.01%)	⬆️
pennylane/gradients/parameter_shift.py	100.00% <100.00%> (ø)
pennylane/gradients/parameter_shift_cv.py	99.16% <100.00%> (ø)
pennylane/operation.py	95.99% <100.00%> (+0.06%)	⬆️
... and 40 more

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[antalszava]

Merging this as the codefactor issues are unrelated to this PR and are being addressed in #2258.