Delayed event management: split endpoints, no auth (#5066)

* Delayed event management: split endpoints, no auth

Add dedicated endpoints for each of the cancel/restart/send actions for
updating a delayed event, and make them unauthenticated.

Also keep support for the original endpoint where the update action is
in the request body, and make the split-endpoint versions fall back to
it if they are unsupported by the homeserver.

* Don't @link parameters in method docstrings

as TypeDoc doesn't support that

* Reduce code duplication

* Reduce code duplication again

* Add a little more test coverage

* Use split delayed event management for widgets

* Specify which eslint rule to ignore

Co-authored-by: Will Hunt <2072976+Half-Shot@users.noreply.github.com>

* Restore embedded non-split delay evt update method

Keep supporting it to not break widgets that currently use it.
Also add back the test for it.

* Deprecate the non-split delay evt update methods

* Comment to explain fallback to non-split endpoint

* Add backwards compatibility with authed endpoints

* Comment backwards compatibility helper method

* Await returned promises

because `return await promise` is at least as fast as `return promise`

---------

Co-authored-by: Will Hunt <2072976+Half-Shot@users.noreply.github.com>

src/errors.ts

@@ -59,7 +59,14 @@ export class ClientStoppedError extends Error {
 export class UnsupportedDelayedEventsEndpointError extends Error {
     public constructor(
         message: string,
-        public clientEndpoint: "sendDelayedEvent" | "updateDelayedEvent" | "sendDelayedStateEvent" | "getDelayedEvents",
+        public clientEndpoint:
+            | "sendDelayedEvent"
+            | "updateDelayedEvent"
+            | "cancelScheduledDelayedEvent"
+            | "restartScheduledDelayedEvent"
+            | "sendScheduledDelayedEvent"
+            | "sendDelayedStateEvent"
+            | "getDelayedEvents",
     ) {
         super(message);
         this.name = "UnsupportedDelayedEventsEndpointError";