[media-library] add doc comments in source, correct types

[Simek]

Why

Fixes ENG-1458

To utilize the auto generation feature for API section on the docs website the package source code must contain the relevant documentation.

How

This PR moves the current documentation of MediaLibrary API - https://docs.expo.io/versions/latest/sdk/media-library - with minor tweaks and additions to the package source code.

This was one of the most demanding conversion so far mainly by the shear amount of content and types variation, however not 100% complete, there are still small parts and descriptions missing, it should be way more complete than the current version of the page.

To full support the migration to automated docs extraction I had to introduce few improvements and fixes to the code:

• add missing AlbumType and MediaSubtype
• add missing orientation key to the Asset type
• add missing return types for few methods
• simplify PermissionResponse and MediaLibraryAssetsChangeEvent types
• export missing types: EXPermissionResponse, Subscription

I have also added small fix for the Event Subscription section, which should now include also method using plural of listerner.

However there is still a room for improvement, especially I have in mind MediaType and SortBy constants, which definitely should be redefined to way simpler construction, so I did not touch their "internal" types like MediaTypeValue, MediaTypeObject or SortByValue.

Also I'm not sure why removeSubscription method exist, it was not earlier listed in the docs.

Test Plan

The changes and generated content have been tests running docs website on localhost.

Preview

Checklist

• Documentation is up to date to reflect these changes (eg: https://docs.expo.io and README.md).
• This diff will work correctly for expo build (eg: updated @expo/xdl).
• This diff will work correctly for expo prebuild & EAS Build (eg: updated a module plugin).

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• packages/expo-yarn-workspaces/CHANGELOG.md

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[bbarthec]

Great job 👍 Many thanks for your hard work on this demanding module 👏