WinUI export: alternate token names about fluentui-token-pipeline

[TravisSpomer]

This is now finished in the platform-overrides branch, but that branch isn't quite ready for a PR yet. The final syntax is this, using fullName and a platform override:

"Width": { "aliasOf": "Set.OutlineActionControl.Stroke.Width",
	"platform": {
		"winui": {
			"fullName": "CheckBoxBorderThemeThickness"
		}
	} 
}

[TravisSpomer]

I'm going to merge that branch, but with the override functionality inoperable for now. You can see it in action by adding this to config.ts after inputTokenFiles.forEach(...):

tokens = resolvePlatformOverrides(tokens, "winui")

I still need to change the platform override functionality to happen only once per platform, which requires changing how we call Style Dictionary, as currently the time that we need to implement platform overrides is too early to know which platform we're building (and any changes then would affect every platform).

[TravisSpomer]

Oops, this is already done, and the workaround to change config.ts is no longer required either. The syntax uses fullName as described in a previous comment.

Closing.