Initial breakout for room list rewrite

This does a number of things (sorry):
* Estimates the type changes needed to the dispatcher (later to be replaced by https://github.com/matrix-org/matrix-react-sdk/pull/4593)
* Sets up the stack for a whole new room list store, and later components for usage.
* Create a proxy class to ensure the app still functions as expected when the various stores are enabled/disabled
* Demonstrates a possible structure for algorithms

src/i18n/strings/en_EN.json

@@ -406,6 +406,7 @@
     "Render simple counters in room header": "Render simple counters in room header",
     "Multiple integration managers": "Multiple integration managers",
     "Try out new ways to ignore people (experimental)": "Try out new ways to ignore people (experimental)",
+    "Use the improved room list component (refresh to apply changes)": "Use the improved room list component (refresh to apply changes)",
     "Support adding custom themes": "Support adding custom themes",
     "Enable cross-signing to verify per-user instead of per-session": "Enable cross-signing to verify per-user instead of per-session",
     "Show info about bridges in room settings": "Show info about bridges in room settings",
@@ -1116,6 +1117,7 @@
     "Low priority": "Low priority",
     "Historical": "Historical",
     "System Alerts": "System Alerts",
+    "TODO": "TODO",
     "This room": "This room",
     "Joining room …": "Joining room …",
     "Loading …": "Loading …",