This commit reworks the macaroon authentication framework to use the
v2 macaroon format and bakery API. It also replaces the code in each
RPC method which calls the macaroon verifier with interceptors which
call the macaroon verifier instead. In addition, the operation
permissions are reworked to fit the new format of "allow" commands
(specifically, entity/operation permissions instead of method
permissions).
In this commit we remove all instances of the macaroon authentication
service from the UnlockerService struct. We do this, as in the future,
the macaroons themselves will be encrypted using the user’s passphrase,
therefore we wouldn’t be able to _verify_ the macaroon unless the
wallet itself was encrypted.
The walletunlocker package contains the UnlockerService, which
implements the lnrpc.WalletUnlocker interface. This service is
used for receiving a password from the user over RPC, and doing
simple validity checks like making sure the user is not trying
to create a new wallet if one already exists, and that in case
the wallet exists, the provided password is correct.
The service will the pass the passwords over the CreatePasswords
or UnlockPasswords channels, for use within lnd.go.
