feat: analytics docs, simplify events

[estrattonbailey]

Fixes APP-122

What changed (plus any additional context for devs)

Consolidates event enums and replaces usages. Add usage docs.

Copied from docs:

import { analyticsV2 } from '@/analytics';

analyticsV2.identify({
    ...userProperties,
})

analyticsV2.track(analyticsV2.event.applicationDidMount)
analyticsV2.track(analyticsV2.event.appStateChange, {
    category: 'app state',
    label: 'foo',
})

analyticsV2.screen(Routes.SWAPS_PROMO_SHEET, {
    ...metadata,
})

What to test

Tests pass, app runs.

[linear]

APP-122 Implement new Segment interface

https://gist.github.com/skylarbarrera/4c17ddd247ef3e50f231612180846464

[jkadamczyk]

Looks good!

[skylarbarrera]

[estrattonbailey]

/rebase