[expo-modules-core] Add stopObserving and startObserving functions

[aleqsio]

Why

Matching iOS implementation for startObserving and stopObserving functions

How

Added calling those functions to CoreModule's EventEmitter class.

Test Plan

Added unit tests.

Checklist

• Documentation is up to date to reflect these changes (eg: https://docs.expo.dev and README.md).
• Conforms with the Documentation Writing Style Guide
• This diff will work correctly for npx expo prebuild & EAS Build (eg: updated a module plugin).

[expo-bot]

The Pull Request introduced fingerprint changes against the base commit: d34b738

Fingerprint diff

[
  {
    "type": "dir",
    "filePath": "../../packages/expo-modules-core",
    "reasons": [
      "expoAutolinkingIos",
      "expoAutolinkingAndroid"
    ],
    "hash": "4dc570f56132dec21b5fde6d9226f7b73aa8eb35"
  }
]

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Generated by PR labeler 🤖

[tsapeta]

We may want to move these tests to https://github.com/expo/expo/blob/main/packages/expo-modules-core/src/__tests__/EventEmitter-test.web.ts

Also notice these silenced tests:

expo/packages/expo-modules-core/src/__tests__/EventEmitter-test.web.ts

Lines 87 to 88 in 3a2579c

	// TODO: Enable these tests once Web supports `startObserving` and `stopObserving`.
	xdescribe('observing', () => {

[expo-bot]

Hi there! 👋 I'm a bot whose goal is to ensure your contributions meet our guidelines.

I've found some issues in your pull request that should be addressed (click on them for more details) 👇

⚠️ Suggestion: Missing changelog entries

Your changes should be noted in the changelog. Read Updating Changelogs guide and consider adding an appropriate entry to the following changelogs:

• packages/expo-sensors/CHANGELOG.md

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Generated by ExpoBot 🤖 against 7a7152c

[aleqsio]

@tsapeta I fixed a failing test case in sensors – think the current test is the expected behaviour, not sure why the expectation was different 5y ago.

[aleqsio]

we could remove it and make it optional