Sander Postma authored May 02, 2022 and Ethan Reesor committed May 02, 2022

Closes AC-1245. Move credits, the nonce/timestamp, and the Signer implementation from LiteTokenAccount to LiteIdentity. This allows a lite identity to be used as the signer or the recipient of AddCredits. For backwards compatibility, allow the lite token account to be used as a signer URL.

## Review Checklist

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Related to AC-1245