Fix dark status bar icon colours in dark mode in onboarding

[mikescamell]

Task/Issue URL: https://app.asana.com/0/488551667048375/1208019450206551/f

Description

The status bars icons were dark in dark mode in onboarding. We were explicitly setting the status bar icon colours to dark regardless of light/dark mode. We can just let the default handle this for us based on mode.

While doing the changes I noticed we were using some deprecated functions/settings so I removed and updated them where appropriate.

Steps to test this PR

• [ ] Ensure you’ve not launched the app previously (clear and wipe data)
• [ ] Set device to dark mode
• [ ] Launch app
• [ ] The status bar icons should be light
• [ ] Switch to light mode
• [ ] The status bar icons should be dark

UI changes

Before	After
Pixel 5 API 26 (Emulator)	Pixel 5 API 26 (Emulator)
OnePlus 6 API 30 (Device)	OnePlus 6 API 30 (Device)
OnePlus 6 API 30 (Device)	OnePlus 6 API 30 (Device)
Pixel 4a API 33 (Device)	Pixel 4a API 33 (Device)
Pixel 4a API 33 (Device)	Pixel 4a API 33 (Device)

[mikescamell]

• #4896 👈
• develop

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