Burn $AUTH needed to release value in unused tokens

[ross-spencer]

$AUTH tokens that are not used by the end of their validity, or ignored in favor of newer mints are not burned and COOP hasn't the capability to burn these as of yet. A burn method is required to release the value left in these tokens.

E.g. the sort of remainder a user might see in their COOP node:

There should be a burn-auth API function but there isn't a corresponding CLI command so it is difficult for the regular user to access.