Enable or disable write access for public deploy keys

Description

After gitlab-foss!7383 (merged) will be merged into master, there would be nice if we could enable or disable write access for the public deploy keys (added through admin interface) for each project. If we add public deploy key with write access it will be able to push to any repo granted to it and if we give it read-only access it will not able to write to any project at all.

Links / references

gitlab-foss#1376 (closed)

/cc @godfat

added 480950 gitlab-foss14213 ~14106 labels

Agreed. Also this means we should probably move can_push from keys to deploy_keys_projects.

Why only "public" (global?) deploy keys? I have some project-specific deploy keys that were added before write-access was available, and I would like to add write-access to them (at least for some projects).

(My GitLab instance is shared across a large company; no one I know has access to the Admin pages.)

moved from gitlab-foss#26116 (moved)