Fix "Edit" button on blame page without repo permissions

What does this MR do?

Without repo permissions, on a blame page, clicking "Edit" will bring up the Fork/Cancel button just like it does on the blob:show page.

Are there points in the code the reviewer needs to double check?

Why was this MR needed?

Without repo permissions, on a blame page, clicking "Edit" would do nothing.

Does this MR meet the acceptance criteria?

• Tests
  • Added for this feature/bug
  • All builds are passing
• Conform by the merge request performance guides
• Conform by the style guides
• Branch has no merge conflicts with master (if it does - rebase it please)
• Squashed related commits together

What are the relevant issue numbers?

Closes #30636 (closed)

assigned to @annabeldunstone

added 9 commits

• 095cef1a...84da388d - 8 commits from branch master
• b4f0ecde - Fix edit button on blame page without repo perms

Compare with previous version

LGTM; will merge when EE conflicts are fixed 👍

marked the task All builds are passing as completed

merged

mentioned in commit b728e30e

Picked into 9-1-stable, will go into 9.1-RC1

removed ~149423 label

mentioned in commit a43b3dcf