feat: allow immutable file upload for wandb logger

[cgebbe]

What does this PR do?

Current Problem

• given wandblogger with log_models=True and e.g. one ModelCheckpoint with save_top_k=3
• when finalizing a run
• then many models will be uploaded to wandb and beforehand copied to a local temporary directory
• and this copying can easily lead to a full disk space and thus a failed run.

Solution

• Allow to specify immutable as policy for add_file to prevent copying.

Open questions

• I didn't add a test, since the wandb logger is a stub and this feels like a very safe modification. Is that okay? Otherwise, what do you suggest?

Before submitting

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PR review

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📚 Documentation preview 📚: https://pytorch-lightning--20193.org.readthedocs.build/en/20193/

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 79%. Comparing base (ea59e40) to head (6c022d0).
Report is 43 commits behind head on master.

❗ There is a different number of reports uploaded between BASE (ea59e40) and HEAD (6c022d0). Click for more details.

HEAD has 2247 uploads less than BASE

Flag	BASE (ea59e40)	HEAD (6c022d0)
cpu	525	24
lightning_fabric	67	0
pytest	266	0
python3.9	132	6
lightning	394	18
python3.10	66	3
python3.11	132	6
python3.12.7	195	9
gpu	2	0
pytorch2.1	99	9
pytest-full	261	24
pytorch2.2.2	33	3
pytorch_lightning	66	6
pytorch2.3	33	3
pytorch2.4.1	31	3
pytorch2.5.1	65	6

Additional details and impacted files

@@            Coverage Diff            @@
##           master   #20193     +/-   ##
=========================================
- Coverage      88%      79%     -9%     
=========================================
  Files         267      264      -3     
  Lines       23380    23326     -54     
=========================================
- Hits        20481    18367   -2114     
- Misses       2899     4959   +2060     

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