Bug 27476: Implement about:torconnect captive portal within Tor Browser

• implements new about:torconnect page as tor-launcher replacement
• adds tor connection status to url bar and tweaks UX when not online
• adds new torconnect component to browser
• tor process management functionality remains implemented in tor-launcher through the TorProtocolService module
• the onion pattern from about:tor migrated to an .inc.xhtml file now used by both about:tor and about:torconnect
• various design tweaks and resusability fixes to onion pattern
• adds warning/error box to about:preferences#tor when not connected to tor
• explicitly allows about:torconnect URIs to ignore Resist Fingerprinting (RFP)
• various tweaks to info-pages.inc.css for about:torconnect (also affects other firefox info pages)

Closes #27476 (closed)