dillon1000/react

Rename Scheduler methods more accurately (#12770)

* Rename Scheduler methods more accurately

**what is the change?:**
```
rIC -> scheduleCallback
```
We will later expose a second method for different priority level, name
TBD. Since we only have one priority right now we can delay the
bikeshedding about the priority names.

cIC -> cancelScheduledCallback
This method can be used to cancel callbacks scheduled at any priority
level, and will remain named this way.

why make this change?:
Originally this module contained a polyfill for requestIdleCallback
and cancelIdleCallback but we are changing the behavior so it's no
longer just a polyfill. The new names are more semantic and distinguish
this from the original polyfill functionality.

**test plan:**
Ran the tests

**why make this change?:**
Getting this out of the way so things are more clear.

**Coming Up Next:**
- Switching from a Map of ids and an array to a linked list for storing
callbacks.
- Error handling

* callback -> work

* update callsites in new places after rebase

* fix typo