[Cashtab] Render paywall id directly as hex
Summary:
Following on from D16623:
I have corrected this on eCashChat's side so the opreturn script has the article txid in hex form...
This diff updates Cashtab to render the paywall article txid directly from hex format
Test Plan: npm test
Reviewers: bytesofman, #bitcoin_abc
Reviewed By: bytesofman, #bitcoin_abc
Differential Revision: https://reviews.bitcoinabc.org/D16558