Formalise CollecTor spec for sanitised bridge descriptors and put in torspec
Perhaps we should make https://collector.torproject.org/#type-bridge-network-status a bit more formal and put it into the torspec repo somewhere?
See this comment by iwakeh on #22207 and this comment by karsten on #18797 and karsten's ANTLR 4 grammar for bridge networkstatuses (note that the grammar will work for both sanitised and unsanitised bridge networkstatuses).
The related ticket, for making a spec for unsanitised bridge descriptors, is legacy/trac#22826 (moved).