Add completions for git fork #2291
Based on the manual page for git fork, this pull request adds
Because this is an array of flags now, adding new flags is as simple as adding more elements to the array and to the case statement.
The --remote-name and --org parameters to git fork expect arguments which can be considered free text because the user has to suggest a name, so we can't provide suggestions there. If one of those two was the previous word then we clear completion suggestions until a free-text word has been entered, allowing the user to add their own input there.
Because it wouldn't make sense to set a name for a remote when you ask it not to add a remote (or vice versa) these two flags are mutually exclusive. For lack of an idea for a more elegant solution, I've made it so that whenever either of them matches, the other will also be dropped from the available flags list. This works perfectly for now but will probably need to be revisited if any other such parameters are added in future.
Now that there are 3 different flags all starting with the same two dashes, the previous test case (that pressing Tab will expand to --no-remote) will fail. The previous test case has been replaced with one that expects a list of completion options matching those provided for git fork.