Merge 5.2.0minus 25

[liam923]

As title suggests, this PR merges oxcaml changes from 5.2.0minus-25. This was a fairly easy merge.

Reviewing

• The first three commits can definitely be skipped, as they are just a result of running the merge script.
• The fourth commit (d8b52bb) resolves what I considered to be trivial conflicts that I didn't find worth reviewing. Feel free to skip this commit too.
• I suggest reviewing the fifth commit (ae8671a) separately from the rest. This one undoes some changes made during the minus-24 merge in commit 45b1502, as oxcaml PR Stop forcing during env folds oxcaml#5066 made superceded those changes.
• The rest of the changes were straightforward fix-ups. These can be reviewed together in one batch.

[github-actions]

Compiler Merge Checklist

This PR seems to merge changes from Flambda. Please be sure to follow the below steps:

• Update the magic numbers
• Update list of compiler flags to ignore
• Make Merlin know about new relevant compiler flags

If this PR is not merging changes from Flambda, feel free to ignore this comment

[dkalinichenko-js]

Everything looks good to me.