[e.cash] Add image priority

Summary:
I noticed some top level images weren't loading first on some pages. Added the priority attribute from next.js
to a few places to help prevent this

Test Plan:
preview the site and check the updated places
you may be able to decern an improvemnt in image priority

Reviewers: #bitcoin_abc, bytesofman

Reviewed By: #bitcoin_abc, bytesofman

Subscribers: bytesofman

Differential Revision: https://reviews.bitcoinabc.org/D14264