Improve the UX of the location bar's connection status

As part of #41060 (closed), we explored beefing up the styling of the connection status in the location bar – and revealing a tiny Connect button when the user navigates away from about:torconnect.

Changes include:

• Adding the new torconnect icon(s)
• Revealing an extra tiny button after tabbing away from about:torconnect
• Adding an additional Potentially Blocked (which should exist in about:preferences#connection's status strip already)
• Additional styling updates

The Figma file's ready for dev handoff here: Figma link

These fixes will be ran through additional usability testing in March/April as part of ~"Sponsor 30" before they reach stable in 12.5.