Update extension Json to make way for changes on extensions page and environments page

Summary of the pull request

This change is the first change to allow us to provide more information to users about extension that are not already installed in Dev Home. See issue #3911 for more details or see the spec I sent out to DevHomeAll for even more info on what's to come (or ping me for the link). Most of the change is just the json files and their C# counter parts.

Changes:

Added a Json file called ExtensionInformation.json. This json file outlines information about currently known Dev Home extensions.
Use the WinGet service to get the package display name, publisher name and description for the package. In the future we can use WinGet to also get the icons for the package. Assuming they are checked into the WinGet catalog.
Added A Json schema file ExtensionInformation.schema.json so that the above json file can be validated against.
Added tests that should be runnable in the pipeline so changes to the ExtensionInformation.json adhere to the schema in ExtensionInformation.schema.json.
Added C# classes that the ExtensionInformation.json will be deserialized into so it can be used in code.
The ExtensionService now returns a DevHomeExtensionContentData which just contains the data from the json in C# classes/properties. This is used by the ExtensionLibraryViewModel to show the list of non-installed extensions in its "Available in the Microsoft Store` section

Here is a video showing me go to the extensions page to confirm functionality is not regressed:

microsoft / devhome

Update extension Json to make way for changes on extensions page and environments page #3923

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