[Cashtab] [Cashtab] [final bch-api deprecation p6] Update API error component to be more descriptive

Summary:
T2730, T2735

Depends on D12792

Change API error text to be specific to chronik

Test Plan:
npm start
Note API error now matches 'Error in chronik connection'

Reviewers: #bitcoin_abc, emack

Reviewed By: #bitcoin_abc, emack

Differential Revision: https://reviews.bitcoinabc.org/D12793