Port the KWallet Keyring to the new CredentialProvider API.

connected account with wallet locked, verified that we weren't prompted for a password until the wallet was unlocked.
connected account, didn't save password, made sure it connected and wasn't stored in kwalletmanager5
connected account, saved password, made sure it connected and verified the password was stored in kwalletmanager5
reconnected account, made sure the account connected without prompting
reopened pidgin, made sure the account connected without prompting.
disconnected pidgin from kwalletmanager5, re-connected account, verified it reconnected via debug and kwalletmanager5
force closed the wallet in kwalletmanager5, re-connected account, unlocked wallet, verified no password prompts and that the account connected.
removed the account and verified the password was removed from kwalletmanager5