refactor(timers): Refactor timers to use one async op per timer

This change also makes the timers implementation closer to the spec, and
sets up the stage to implement `AbortSignal.timeout()`
(whatwg/dom#1032).

Fixes #8965.
Fixes #10974.
Fixes #11398.

cli/tests/testdata/test/ops_sanitizer_unstable.out

@@ -11,16 +11,16 @@ Before:
   - dispatched: 1
   - completed: 1
 After:
-  - dispatched: 3
-  - completed: 2
+  - dispatched: 4
+  - completed: 3
 Ops:
-  op_global_timer:
+  op_sleep:
     Before:
       - dispatched: 1
       - completed: 1
     After:
-      - dispatched: 3
-      - completed: 2
+      - dispatched: 4
+      - completed: 3
 
 Make sure to await all promises returned from Deno APIs before
 finishing test case.

cli/tests/testdata/worker_drop_handle_race.js.out

@@ -2,7 +2,7 @@ error: Uncaught (in worker "") Error
   throw new Error();
         ^
     at [WILDCARD]/workers/drop_handle_race.js:2:9
-    at fire (deno:ext/timers/[WILDCARD])
+    at Object.action (deno:ext/timers/[WILDCARD])
     at handleTimerMacrotask (deno:ext/timers/[WILDCARD])
 error: Uncaught (in promise) Error: Unhandled error event in child worker.
     at Worker.#pollControl (deno:runtime/js/11_workers.js:[WILDCARD])