Objective 1, Activity 1.1: Make v3 the default on Core Tor stable

This is the parent ticket to hold any tickets under this activity, including:

Making onion services v3 the default option on Core Tor
Implementing a set of fixes to issues we have documented at our issue tracker, in order to:
- Reduce onion service exposure to malicious relays
- Create faster and more reliable client connections
- Create more reliable client connections for bridge users

To upload designs, you'll need to enable LFS and have an admin enable hashed storage. More information