docs: updated INPUT_API_REFERENCE.md to acknowledge web (#605)

# Summary
- only review once the PRs below are fully merged
- Replaces all `Both` platform labels with explicit lists, so it's
future-proof for macOS support
- Adds an experimental web support notice at the top with a note that
`EnrichedText` is coming to web
- Documents three open PRs as if they were merged:
  - **#584** `feat(web): image paste`
  - **#600** `feat(web): submit props`
  - **#603** `feat(web): shortcuts`
## Test Plan

N/A

## Screenshots / Videos

N/A

## Compatibility

N/A 

## Checklist

N/A

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Co-authored-by: Krystian Sienkiewicz <krystian.sienkiewicz@swmansion.com>
Co-authored-by: Kacper Żółkiewski <kacper.zolkiewski@swmansion.com>

Author: 3 people