[Cashtab] Make agora tiles more useful

Summary:
Diff does 2 things bc they both are important to improving UX around increasing number of agora offers.

• We include a displayed abbreviated tokenId and a copy tokenId button. This can help users distinguish between attempted scams.
• We change the link to open the token page of an agora offer in Cashtab, which shows the offer and more info about the token, instead of the block explorer which does not really show much at all

Test Plan:
npm test, review screenshot

before

after

Reviewers: #bitcoin_abc, emack

Reviewed By: #bitcoin_abc, emack

Subscribers: emack

Differential Revision: https://reviews.bitcoinabc.org/D17271