[feat] add a "read-only" tickbox in remote settings (for forked remotes)

[Albirew]

is it possible to add a "read-only" tickbox in remote settings?
this way, when pushing changes or deleting tags to all remotes, read-only upstream remotes would not be tried, and no error would be shown.

example: when forking a project to add own changes, but still keeping with upstream updates