Move all reporting from Wallet::Admin to Wallet::Report and simplify
the method names since they're now part of a dedicated reporting
class.  Similarly, create a new wallet-report script to wrap
Wallet::Report, moving all reporting commands to it from wallet-admin,
and simplify the commands since they're for a dedicated reporting
script.

Remove the contrib script wallet-report to wallet-summary so that it
doesn't conflict with the new reporting backend script.