[e.cash] Live transactions card

Summary:
Depends on D19338

Add a live transactions view to the "Shape the future of digital cash" card carousel section on landing page

• added chronik client global context
• fetch the mempool and then start listening for new transactions via ws
• display transactions on the card
• show the latest 4 at a time

Test Plan: preview and check

Reviewers: #bitcoin_abc, bytesofman

Reviewed By: #bitcoin_abc, bytesofman

Subscribers: Fabien, bytesofman

Differential Revision: https://reviews.bitcoinabc.org/D19317