Rebasing with BRH

[rfrench3]

previously mentioned in #3,

The system rebase requires the user to input their password, and -deck users should not be assumed to know that password (bazzite) because they did not set it.

[rfrench3]

This also means that it instantly fails in gamescope session with no indication of why.

[rfrench3]

The rebase page now disables the rollback/rebase buttons when brh is not present (and informs the user of that), and will specifically disable rebasing in gamescope session when a proper check for it is implemented.

[rfrench3]

Rebasing has been removed until the entire system for rebasing is properly implemented.