Using the `Open File` action from a file in commit context takes you to
a read-only snapshot of the file at the point in time of the commit.
This change makes it so you navigate to the current working copy of the
file, if one exists. This has similar semantics to copy file reference.

For a file that still exists at HEAD:
<img width="715" height="469" alt="image"
src="https://github.com/user-attachments/assets/e217e0be-b549-46fa-9d1b-eba92728fa4a"
/>

For a file that no longer exists:
<img width="438" height="271" alt="image"
src="https://github.com/user-attachments/assets/ac87465b-971b-4413-8bf3-71e49a71bdea"
/>

Release Notes:

- Add affordance to jump to project file from commit view