[ecash-herald] Add directory of known-ish addresses

Summary:
For some addresses, a 'tag' is more interesting than a preview string like qq3...x4u

Add a directory to begin organizing these addresses.

Test Plan: npm test, npm run sendMsgByBlock 799514 output pictured

Reviewers: #bitcoin_abc, PiRK

Reviewed By: #bitcoin_abc, PiRK

Differential Revision: https://reviews.bitcoinabc.org/D14214