Implement an "Invite Friends/Referral" page

[Murkantilism]

The idea here is for a user to share their unique link to invite other users.

Firebase Dynamic Links will work for this: https://firebase.google.com/docs/dynamic-links/use-cases/user-to-user

Invitation & referral links: https://firebase.google.com/docs/dynamic-links/use-cases/rewarded-referral

See video overview

Acceptance Criteria

Continue building this page:

• Users need a unique link to use for inviting friends.

• We need to track each referral from the unique links and attribute credit back to the user.

[BrennenHodge]

@Murkantilism @myeduguri I've edited/updated this issue. The page https://covidx.app/invite-friends is already created. Per @Mariefay in the video, we need a point counting system in the backend. We can discuss this during our meeting today.