refactor: extract action buttons

[DSIW]

• Extract action buttons
• Move to components

Feature summary

QA checklist

• [x] Read state (state & power state)
• [ ] Read primary battery SOC
• [ ] Read primary battery cycles
• [ ] Read secondary battery SOC
• [ ] Read secondary battery cycles
• [x] Read seat closed
• [x] Read handlebar
• [x] Read AUX SOC
• [x] Read CBB SOC
• [ ] Read CBB charging state
• [ ] Update ping
• [ ] SOCs are cached (after app restart)
• [x] Commands can be sent (locking & hibernation)

[TheFreal]

1. This feels like really poor style, as it turns what was previously one reusable widget into a whole folder of single-purpose files.
2. The action buttons will probably change significantly in #43 (which this structure would make way harder)
3. I'm not yet convinced of the flutter-on-wear approach in its entirety For those reasons, I'm not merging for now :/