Add a `add deploy key` interface to `glab`

Proposal

Please add a add deploy key interface to glab.

The current Web UI for adding a deploy key to projects is a real PITA:

• If I have thousands of deploy keys:
  • I have to search for them in a paginated web UI manually (by eyes).
    • There’s no search UI for this.
    • I can’t just upload a public key as a file because I get an error: "this key" (what key??) already exists.
  • I have to do additional searches and clicks to enable write access.

Instead of improving this UI, it would probably be more effective to implement a glab command in the current project, like this:

glab add-deploy-key --write-access «public_key_file.pub»