When bitFlyer access token has expired or reauth is required from user, make sure wallet goes into "Disconnected" state

Description

In several cases, the user’s bitFlyer access token will be expired and the user will need to reauth.

The UI does not seem to detect this, and does not move the user into a Disconnected state so that they know to reauth. As a result, some requests to bitFlyer (such as sending a tip) can fail silently in the background, and there is no indication to user that they will need to reauth.

Message @A-t-s-u-s-h-i and @Miyayes for more specifics.

[LaurenWags]

@brave/legacy_qa the test plan is available under https://github.com/brave/internal/issues/803. All verification notes can be added to that internal issue as well.

[LaurenWags]

Verified passed with

Brave | 1.31.66 Chromium: 94.0.4606.61 (Official Build) beta (x86_64)
-- | --
Revision | 418b78f5838ed0b1c69bb4e51ea0252171854915-refs/branch-heads/4606@{#1204}
OS | macOS Version 10.15.7 (Build 19H1417)

Verification notes can be found under https://github.com/brave/internal/issues/803#issuecomment-930178983