Adding searchable flag to users table: opt in/out from being searched in org invitations

Created by: pietrorosa77

This PR adds a new flag to the users catalog and a corresponding page under user settings to control it. The flag named searchable is used to control whether the user wants to appear or not into the users search autocomplete that will be implemented in the organization invitation page. The flag defaults to true and it's not nullable

https://www.loom.com/share/a6bc48da514946efb56f05943282b172

Test plan

This PR has been manually tested but a follow up PR will be added with UT