CHW-4216 InvitationRoleUnavailable

the invitation's role is no longer available; ask the inviter to re-issue with a current role

Default message: the invitation’s role is no longer available; ask the inviter to re-issue with a current role
HTTP status: 400 (client)

Problem. The invitation references a role that no longer exists. Cause. The custom role was deleted or renamed after the invitation was issued. Fix. Ask the inviter to re-issue with a current role. HTTP 400.