Dynamic Runtime Samples

[TomAtkinsonArm]

Description

There is a high chance that we want to reuse cross platform components in many executables. CUSTOM_MAIN aims to reduce duplication of a cross platform main.

CUSTOM_MAIN(context)
{
	// _default is a temporary pattern, this is likely to be replaced in the future

	auto window = windows::_default(context, "A Window");        // < window platform default
	auto fs     = vfs::_default(context);                        // < virtual fs platform default
	auto camera = cameras::_default(context);                    // < get a devices camera AR?
}

Adds sample_main(context). Works similar to a normal main function except it hides the cross platform support.

The minimum code needed for a sample is

#include "components/platform/sample_main.hpp"

#include <iostream>

int sample_main(const components::PlatformContext *context)
{
	return true;
}

Later a Sample Launcher will read library paths and sample info from a JSON file. Allow the user to select a sample to run and then run the sample by loading the dynamic library and calling sample_main. We can extend this to allow for CLI configuration and more.

[TomAtkinsonArm]

Closed #488 as this PR includes its changes. Updated description