fixup! Bug 31286: Implementation of bridge, proxy, and firewall settings in...

fixup! Bug 31286: Implementation of bridge, proxy, and firewall settings in about:preferences#connection

Bug 41802: Improve the regex on parseBridgeLine

The previous version of the regex took for granted the bridge
fingerprint was always available, but it is actually optional.
So, parsing some bridge lines (e.g., Conjure) failed, and vanilla
bridge was displayed instead of the actual transport.