Improve error messages for SST footer and size errors (#11009)

Improve error messages for SST footer and size errors (#11009)

Summary:
Previously, you could get a format_version error if SST file size was too small in manifest, or a weird "too short" error if too big in manifest. Now we ensure:
* Magic number error is reported first if we attempt to open an SST file and the footer is completely bad.
* Footer errors are reported with affected file.
* If manifest file size doesn't match actual, then the error includes expected and actual sizes (if an error is reported; in some cases we allow the file to be too big)

Pull Request resolved: https://github.com/facebook/rocksdb/pull/11009

Test Plan:
unit tests added, some manual

Previously, the code for "file too short" in footer processing was only covered by some tests attempting to verify SST checksums on non-SST files (fixed).

Reviewed By: siying

Differential Revision: D41656272

Pulled By: pdillinger

fbshipit-source-id: 3da32702eb5aaedbea0e5e74742ad57edd7ad3df