MSC4108 implementation (#17056)

Cargo.lock

changelog.d/17056.feature

rust/Cargo.toml

rust/src/lib.rs

rust/src/rendezvous/mod.rs

rust/src/rendezvous/session.rs

synapse/config/experimental.py

synapse/http/server.py

synapse/rest/client/rendezvous.py

synapse/rest/client/versions.py

synapse/rest/synapse/client/__init__.py

synapse/rest/synapse/client/rendezvous.py

synapse/server.py

synapse/synapse_rust/rendezvous.pyi

tests/rest/client/test_rendezvous.py

tests/server.py

tests/unittest.py