Allow customizing URL alias patterns for file entities

[ToniTen]

Description of the need

Right now, at /admin/config/urls/path/patterns one can customize the url for nodes, taxonomy and user accounts, but not for file entities. If you make the file display "Download link" so the file is requested through Backdrop, and not straight from the file system, the link ends up revealing the file ID (the link takes the form of https://example.com/file/[ID]/download?token=[token]

Proposed solution

Add an url alias pattern for files. Allow tokens to be used, and add "File display title" as a token.

Alternatives that have been considered

I think modern Drupal handles this through the core, but I stopped following Drupal when I decided that Drupal 8+ wasn't viable for my use case, and I'm rebuilding my sites using Backdrop after Drupal 7 EOL

Draft of feature description for Press Release (1 paragraph at most)

Backdrop now includes support for url aliases for file entities.

[indigoxela]

Hey @ToniTen, welcome to the Backdrop issue queue. 👋

Path aliases for file entities have apparently been omitted on purpose, but can be added via hook.
File path.api.php contains an example for that: https://github.com/backdrop/backdrop/blob/1.x/core/modules/path/path.api.php#L141

I'm not sure if aliases for file paths are an 80% use case, but this functionality would be a great contrib candidate. I'm not aware of any existing project.

Re addition to core: let's wait for some feedback here.