write voucher mgmt helper script

[brenzi]

for a batch of vouchers, we'd like to easily query which ones are reaped and optionally reap all outdated vouchers

in python. will need to use CLI client wrapper lib

input:

• file with one SURI per line, as generated by voucher.py as *.secrets

global args:

• ss58prefix specifies account display format: 42 for default, 2 for kusama

commands:

• info: prints csv to stdout: accountid, balance, <reap_timestamp>, <reap_accountid>, where balance has demurrage applied
• recollect --reap_age 30d --beneficiary ACCOUNTID: reaps all vouchers that haven't sent any extrinsic for the last reap_age days/time