[backend] Add option to use sha512 for repomd metadata

[backend] refactor ecdsa curve handling and add support for nistp384

Show old file name for renamed files in diffs

Don't parse diffs on renamed files

It would be nice to allow also multiple checksum hashes in parallel, but
createrepo_c is not supporting it atm.

Also, the setting to sha512 overrules legacy setting on purpose to be
on the safe side.

[src/api] Update rubocop-rspec: 2.17.0 → 2.18.0 (minor)

This CSS class was missing previously for showing correctly the
"Renamed" badge. This fix applies for both, beta and non-beta.

On renamed files, the 'diff' key of a file in a sourcediff structure is
not defined.

Co-authored-by: Saray Cabrera Padrón <scabrerapadron@suse.de>

[src/api] Update faraday: 2.7.2 → 2.7.3 (patch)

[src/api] Update rspec-mocks: 3.12.2 → 3.12.3 (patch)

Restrict .alert-* classes to alert elements

Parse diffs also in Files Changed between revisions

Co-authored-by: Saray Cabrera Padrón <scabrerapadron@suse.de>

Those classes are sometimes extending rules (like with `@extend
.alert-warning`) and the rules from `flash.scss` affect those extended
rules. This should only be the case for alert elements, which is what we
have now with this commit.

Nothing changes visually for the flash messages.

[backend] BSX509: support ECDSA with the nistp256 curve

Fix loop over diff content

Revert "Update mail to version 2.8.0.1"

Make sure project exists when checking if it's staging

This reverts commit 125534ee.

Fix overflow in revision diff view

Implement parser for request diffs

Colour the superseded by links in a badge correctly

Clarify the meaning of different reviewer types