fix: use stable route for comment search results

[kesselb]

• Resolves: [Bug]: Opening a file from a comment search result does not open or scroll to the file #54378

Summary

The old version with files.view.index (with dir and scrollto) is opening the folder, but does not open the file or scroll to it.

The recommended way to reference a file is files.view.showFile as done by the files search provider and the activites app.

OCA\Comments\Search\LegacyProvider and OCA\Comments\Search\Result are deprecated since 20 and thus I took the opportunity to migrate away from it.

TODO

• Check if the logic to obtain the comments was migrated correctly
• Adding tests
• Remove the deprecated and now unused classes right away
• I assume we are loading the comments in a loop until 50 comments because there's no way, api wise, to obtain only comments with actor_type = users. If we are touching this anyway, then we should consider adding a new api for it to simplify the implementation and save database queries.

Checklist

• Code is properly formatted
• Sign-off message is added to all commits
• Tests (unit, integration, api and/or acceptance) are included
• Screenshots before/after for front-end changes
• Documentation (manuals or wiki) has been updated or is not required
• Backports requested where applicable (ex: critical bugfixes)