Replace podUrl text input with a select input of user's contacts in "sharing" modals

Describe the Current Behavior/Feature:

In both of the "sharing" modals in the Profile page, the user must type in the podUrl of another person they want to set the permissions for.

Proposed Behavior/Feature:

Replace this with a dropdown select input of the user's contacts.

Rationale:

Users will have a hard time remembering the podUrls of others since each server can have a different format, and given our clientele.

Proposed Implementation (if applicable):

1. Create some sort of "contacts" list for each user
2. Populate the select menu options with said "contacts" list

Additional context: