Add @override for remaining files in src/lightning/pytorch

[VictorPrins]

It adds the @override decorator for all files in src/lightning/pytorch (#18695).

As per #18695 (comment), this excludes files in src/lightning/pytorch/utilities and src/lightning/pytorch/demos.

[VictorPrins]

@carmocca Should the files in pytorch/utilities not use override (#18695 (comment))? There are a few eligible methods in that folder, e.g:
https://github.com/Lightning-AI/lightning/blob/af852ff5908e9a99917eeeff05bb4536dbb1cade/src/lightning/pytorch/utilities/model_summary/model_summary_deepspeed.py#L73

[codecov]

Codecov Report

Merging #19065 (70a1c5f) into master (af852ff) will decrease coverage by 33%.
The diff coverage is 100%.

Additional details and impacted files

@@            Coverage Diff             @@
##           master   #19065      +/-   ##
==========================================
- Coverage      82%      49%     -33%     
==========================================
  Files         443      435       -8     
  Lines       36573    36425     -148     
==========================================
- Hits        29811    17822   -11989     
- Misses       6762    18603   +11841