[rfile] set default compression to 505 and add SetCompressionSettings

[silverweed]

Note that GetCompressionSettings() is not provided at this time because it has ambiguous semantics and we need to decide if we want to provide it at all.

Checklist:

• tested changes locally
• updated the docs (if necessary)

[github-actions]

Test Results

    22 files      22 suites   3d 5h 15m 3s ⏱️
 3 828 tests  3 827 ✅ 1 💤 0 ❌
76 601 runs  76 592 ✅ 9 💤 0 ❌

Results for commit ec4b9e9.

♻️ This comment has been updated with latest results.

[silverweed]

NOTE: changed the exception to a warning in case the file is not writable, as the operation is just a no-op and not fatal.

Edit: I changed it again to remove SetCompressionSettings, at least for now, and only allow setting the compression during Recreate. We can decide to add back SetCompressionSettings later if needed.