perf(reactivity): improve reactive effect memory usage (#4001)

Based on #2345 , but with smaller API change

- Use class implementation for `ReactiveEffect`
- Switch internal creation of effects to use the class constructor
- Avoid options object allocation
- Avoid creating bound effect runner function (used in schedulers) when not necessary.
- Consumes ~17% less memory compared to last commit
- Introduces a very minor breaking change: the `scheduler` option passed to `effect` no longer receives the runner function.

packages/runtime-core/__tests__/scheduler.spec.ts

@@ -1,4 +1,3 @@
-import { effect, stop } from '@vue/reactivity'
 import {
   queueJob,
   nextTick,
@@ -576,20 +575,19 @@ describe('scheduler', () => {
 
     // simulate parent component that toggles child
     const job1 = () => {
-      stop(job2)
+      // @ts-ignore
+      job2.active = false
     }
-    job1.id = 0 // need the id to ensure job1 is sorted before job2
-
     // simulate child that's triggered by the same reactive change that
     // triggers its toggle
-    const job2 = effect(() => spy())
-    expect(spy).toHaveBeenCalledTimes(1)
+    const job2 = () => spy()
+    expect(spy).toHaveBeenCalledTimes(0)
 
     queueJob(job1)
     queueJob(job2)
     await nextTick()
 
-    // should not be called again
-    expect(spy).toHaveBeenCalledTimes(1)
+    // should not be called
+    expect(spy).toHaveBeenCalledTimes(0)
   })
 })