Support role-based edits

[josueetcom]

Currently we only allow scholarship updates/deletes for the author of a scholarship. However as site owners we should have full access to editing the scholarships as well.

Some docs to look at:

• https://firebase.google.com/docs/auth/admin/custom-claims
• https://firebase.google.com/docs/firestore/solutions/role-based-access

[josueetcom]

Ok I've found this for accessing the custom claims in the JWT token from the client side: https://firebase.google.com/docs/auth/admin/custom-claims#access_custom_claims_on_the_client