[e.cash] Hero edits

Summary: Adding the spline animation, moving Hero to its own component to match structure, adding mobile styles from the mockup

Test Plan: preview and check it out

Reviewers: #bitcoin_abc, bytesofman

Reviewed By: #bitcoin_abc, bytesofman

Subscribers: bytesofman

Differential Revision: https://reviews.bitcoinabc.org/D18320