set-status: Status-suggestion content rendering in horizontal device insets

[chrisbobbe]

See screenshot (where I'm long-pressing one of the suggestions to show touch feedback):

Proposal:

• In _SetStatusPageState, wrap the Column passed to Scaffold.body in a SafeArea with bottom: false
• Change the text-input row's end margin from 10px to 8px, to match the 8px end margin on the status suggestions (I know this goes against the Figma but I'd prefer consistency 🙂)
• For all page content, take 8px of horizontal external whitespace and move it to the outer SafeArea.minimum
• Remove the InkWell touch feedback on status-suggestion items. I usually like touch feedback, but the Figma doesn't specify it here, and it's not clear if we'd want it to extend through the device insets or not. Thankfully there's no network request so it should always be immediately clear that a tap was detected (the inputs will change).

cc @sm-sayedi as the author of #1701

[sm-sayedi]

Thanks for spotting this and the related issues.