Implement Real Time Updates for all Trip Collaborators

[zghera]

Issue summary

We want real time listening to Firestore so that a user's trips are always up to date.

Expected behavior

The addition of real time listening with onShapshot should allow fetching the most up to date trips where a user is a collaborator whenever a new update to the Trips collection is made.

Actual behavior

Currently when a new trip is created/edited, only the creator of the trip can automatically see the trip on their 'View Trips' page (using the key prop on TripsContainer). For other users, they must refresh the page to see any new trips where they are collaborators.

Steps to reproduce (including any preconditions)

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Your environment

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