[web] introduce community header actions

Summary:
This component houses the invite link button and the community settings button, two possible community action buttons that can be rendered, and all the related logic for that. If a community does not have an active invite link then the invite link button should not be rendered.

The invite link button should push the ViewInviteLinkModal and the community settings button will navigate the user to the community settings screen (will be done in a subsequent diff)

Linear task: https://linear.app/comm/issue/ENG-5933/top-bar

Depends on D10497

Test Plan:
Please see the screenshots + demo video below

When the community has an active invite link

When the community does not have an active invite link

Reviewers: atul, kamil, rohan

Reviewed By: atul

Subscribers: ashoat, tomek

Differential Revision: https://phab.comm.dev/D10498