[explorer] Render token icon next to token inputs, outputs, and in token summary table

Summary:
Render the token icon next to token inputs and outputs, including the mint baton. Also render in the token summary table and the eTokens table on the address page.

Note: a blockie is generated server-side for tokens that do not have an icon.

Test Plan:
cargo run, check out the genesis tx for some tokens with and without icons.

Reviewers: #bitcoin_abc, Fabien

Reviewed By: #bitcoin_abc, Fabien

Subscribers: Fabien

Differential Revision: https://reviews.bitcoinabc.org/D16611