feat(wallet): Show info toast when switching balance unit

[ovitrif]

Description

Added a toast message to clarify balance unit switch actions.

Works in both balance headers:

• Wallet overview (Home)
• Bitcoin assets (Wallet detail)

Toast gets displayed only once: on first use.

Linked Issues/Tasks

Bitkit v45 prototype → Toast for balance unit switch (Asana)

Type of change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Refactoring (improving code without creating new functionality)

Tests

• Detox test
• Unit test
• No test

Screenshot / Video

qemu-system-aarch64.2024-01-17.001418.mp4

QA Notes

See above video

Dev Notes

1. I'm not sure if I broke a few rules on how we approach these things when creating the reusable useSwitchUnitAnnounced hook.
   Happy to get feedback / suggestions for alternative approaches if it feels needed.
2. I'm targeting the PR for the hide balance toast as base branch to avoid having to do 2 redux store migrations and also because that PR isn't yet merged due to unsuccessful e2e tests. This changeset could've been just a push to that PR but then it would make it less easy to review.