Deduplicate several JavaScript files

[tom-un]

Please select one of the following

• I am removing an existing difference between facebook/react-native and microsoft/react-native 👍
• I am cherry-picking a change from Facebook's react-native into microsoft/react-native 👍
• I am making a fix / change for the macOS implementation of react-native
• I am making a change required for Microsoft usage of react-native

There were several JavaScript files in the fork that were direct copies of files upstream: where upstream there was a Foo.ios.js, in this fork we copied it to Foo.macos.js. When merging changes from upstream it is an error prone process to keep these copied files in sync. This change removes the contents of most of these Foo.macos.js files and changes them to simply require('./Foo.ios.js'). There were a couple files that upstream had a Bar.ios.js and Bar.android.js and in the fork we renamed Bar.ios.js to Bar.js to share with mac. These files have been restored to Bar.ios.js and Bar.macos.js has been created that simply does a require('./Bar.ios.js'). A few other .macos.js files had inconsistent comment headers with their other platform counterparts. Finally, there were a few ejected components that still had old .macos.js files hanging around -- they have been deleted.

Focus areas to test

Full automated test suite pass, manual testing of RNTester.

Microsoft Reviewers: Open in CodeFlow

[pull-bot]

	Messages
📖	📋 Missing Changelog - Can you add a Changelog? To do so, add a "## Changelog" section to your PR description. A changelog entry has the following format: [CATEGORY] [TYPE] - Message. CATEGORY may be: General iOS Android JavaScript Internal (for changes that do not need to be called out in the release notes) TYPE may be: Added, for new features. Changed, for changes in existing functionality. Deprecated, for soon-to-be removed features. Removed, for now removed features. Fixed, for any bug fixes. Security, in case of vulnerabilities. MESSAGE may answer "what and why" on a feature level. Use this to briefly tell React Native users about notable changes.
📖	📋 Missing Test Plan - Can you add a Test Plan? To do so, add a "## Test Plan" section to your PR description. A Test Plan lets us know how these changes were tested.
📖	📋 Missing Summary - Can you add a Summary? To do so, add a "## Summary" section to your PR description. This is a good place to explain the motivation for making this change.

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