Introduce per-room lock acquired before committing a transaction

Cargo.lock

@@ -1041,6 +1041,7 @@ dependencies = [
  "client",
  "collections",
  "ctor",
+ "dashmap",
  "editor",
  "env_logger",
  "envy",
@@ -1536,6 +1537,19 @@ dependencies = [
  "syn",
 ]
 
+[[package]]
+name = "dashmap"
+version = "5.4.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "907076dfda823b0b36d2a1bb5f90c96660a5bbcd7729e10727f07858f22c4edc"
+dependencies = [
+ "cfg-if 1.0.0",
+ "hashbrown 0.12.3",
+ "lock_api",
+ "once_cell",
+ "parking_lot_core 0.9.4",
+]
+
 [[package]]
 name = "data-url"
 version = "0.1.1"