Button in file commit history to view file at commit

[silverwind]

Feature Description

When viewing a file's commit history, GitHub has a button to view a file at a specific commit, for example:

https://github.com/go-gitea/gitea/commits/main/README.md

It should be easy to add, just check whether the commit log is for a file, and if so, construct a link to file with the commit hash.

Possibly depends on #24423.

[silverwind]

Also related, when viewing the root commit history, also show this button: