Add invite routing

[achandrabalan]

Notion ticket link

SYNCING UP WORK ON https://www.notion.so/uwblueprintexecs/Create-seperate-standalone-page-for-accepting-an-invite-to-an-existing-shift-c88853f2c1b24726a08d5db02cb97a3d?pvs=4

Implementation description

Steps to test

What should reviewers focus on?

Checklist

• My PR name is descriptive and in imperative tense
• My commit messages are descriptive and in imperative tense. My commits are atomic and trivial commits are squashed or fixup'd into non-trivial commits
• I have run the appropriate linter(s)
• I have requested a review from the PL, as well as other devs who have background knowledge on this PR or who will be building on top of this PR