Add community search

[micahmo]

Pull Request Description

This PR adds the ability to initiate a search from a community. We already have the ability to search communities from the main search page, but I often find that I'm already in a community and want to search just that community without losing my spot. Now there's a new menu item which will push a new search page on the stack.

The community-specific search page will have a few limitations.

• Only search for posts/comments
• No feed type filter
• Search box hint and no results hit now references community name
  • Body hint is hidden
• No community filter

I also refactored the PopupMenuItems

Review without whitespace

Issue Being Fixed

Issue Number: N/A

Screenshots / Recordings

qemu-system-x86_64_jM8TXf31bU.mp4

Checklist

• Did you update CHANGELOG.md?
• Did you use localized strings where applicable?
• Did you add semanticLabels where applicable for accessibility?

[hjiangsu]

Sorry for the delay in reviewing this. LGTM (just merge conflicts to handle and it should be good 😊)!

[micahmo]

Sorry for the delay in reviewing this. LGTM (just merge conflicts to handle and it should be good 😊)!

No problem! Should be all set now!