[TIMOB-9817] Tooling: Create machine-readable file format to describe tiapp.xml platform configuration options

Reviewing TISTUD-568 and TISTUD-1524, it seems worthwhile to create some sort of description that encapsulates the possible values for per-platform configuration options. The goal would be to provide a file Titanium Studio could read, interpret, and then display GUI configuration options for common platform settings as part of an extension of TISTUD-1824 While Studio could natively create a GUI for these items, the mix of an increasing number of supported platforms as well as version differences between SDKs makes this an increasingly problematic direction to take. Some thoughts: * XSD seems a natural option, but JSON is okay as well. We are alsread planning on creating an XSD for the root tiapp.xml file. * Some items may require a drop down list of options, perhaps pulled from available SDKs (see iOS Deployment targets). Perhaps these could be encoded in a format Studio knows how to fill in with live values * Android activities pose a problem, but perhaps there is some simple way that we can describe the common use case.