Add EXPORTED tape states to DB schema

This ticket is linked to the request:

• https://cta-community.web.cern.ch/t/adding-a-new-state-for-exported-tapes/165

And to the ops issue:

• https://gitlab.cern.ch/cta/operations/-/issues/853.

Currently, a tape can have the following states: ACTIVE, BROKEN, DISABLED (new REPACKING and PENDING states are being added in #83 (closed) and #77 (closed)).

While we at CERN we do not remove tape cartridges from tape libraries, other sites do. Therefore, an EXPORTED state would help them to distinguish that.

This state would behave very similarly to BROKEN state. The difference is that the error message needs to be modified/added:

Your file is temporarily unavailable because it is on EXPORTED tape