Pair --type with --remove-type so callers can clear an issue's type
without going through the interactive editor, mirroring the
--milestone / --remove-milestone and --parent / --remove-parent
patterns. The two type flags are mutually exclusive.
UpdateIssueIssueType now sends a null issueTypeId when the caller
passes an empty string, which is what the API requires to clear the
field. The orchestrator fires the mutation when either IssueTypeID is
non-empty or RemoveIssueType is set.
Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>