As admin, I can configure which Requirement Status to map to Custom Test Run Status

Currently, all custom statuses are considered NOT RUN in terms of Requirement Status.

A new Requirement Status named "Unknown" should be provided in Xray.

An administrator must have the possibility to map witch Requirement Status will be used for a given Custom Status. This mapping will be possible on the "Manage Test Statuses" configuration page.

A background issue reindex operation must be performed automatically if a status mapping is changed.

All new Custom Test Run Statuses will be configured by default with Requirement Status "Unknown".