add an error for "rejected by server, unrecoverably"

Submitted by Simon McVittie

Assigned to Telepathy bugs list

Link to original bug (#32044)

Description

In a Haze commit before 0.5.0, wjt wrote

•   * We ought really to have an error case for unrecoverable server errors

•   * where the best we can do is present a human-readable error from the

•   * server.

Related to Bug #21735.

Version: git master