[explorer] Unfold the token balances by default if there is any

Summary: So that the address page shows all the balances upon opening with no additional click required.

Test Plan: Open an address with some tokens and check the balances are unfolded by default.

Reviewers: #bitcoin_abc, PiRK

Reviewed By: #bitcoin_abc, PiRK

Differential Revision: https://reviews.bitcoinabc.org/D16305