[tg bot] introduce app parsing for op_return msgs with cashtab msg parsing

Summary:
T2972

Parse OP_RETURN msg prefixes for known apps. In this diff, introduce Cashtab msgs. Label apps with a spec-fitting prefix that is not known as 'unknown app'. Mark OP_RETURN txs with no prefix as 'no app'

Test Plan:
npm test
npm run msgs

Reviewers: #bitcoin_abc, emack

Reviewed By: #bitcoin_abc, emack

Differential Revision: https://reviews.bitcoinabc.org/D13299