Remove it from request handler since there's already the context of the
request path, added through TraceLayer.

They are no longer needed in the 2021 edition.

Should make the code a little bit easier to read.

TIL body.device_id != (*body).device_id, which is pretty bad, so I
renamed body.device_id to body.sender_device

feat: first steps towards joining rooms over federation
Add state-res as a dependency of conduit
Add reverse_topological_power_sort before append_pdu
Implement statehashstatid_pduid tree for keeping track of state
Clean up implementation of state_hash as key for tracking state