[e.cash] Add Trezor to e.cash/wallets list

Summary: Uploading Trezor logo and adding Trezor to the list of eCash supporting wallets.

Test Plan: visit e.cash/wallets and double check for errors or typos

Reviewers: #bitcoin_abc, bytesofman

Reviewed By: #bitcoin_abc, bytesofman

Subscribers: bytesofman

Differential Revision: https://reviews.bitcoinabc.org/D18078