sdk: add get_module_info, get_plugin_directory, d3d9 callbacks (#908)

## Link to GitHub Issue or related Pull Request, if one exists
n/a

## Description of change
To make plugin development easier, add `get_module_info` and
`get_plugin_directory` to deal with common tasks for hooking DLLs and
reading INI files.

Also, add the ability to register for d3d9 present callbacks via
`register_d3d9`, which makes it significantly easier for plugins to draw
things on screen.

## Testing
See sample code.

src/spice2x/sdk/sdk.h

@@ -7,6 +7,6 @@ namespace sdk {
 
 void register_sdk_hooks(std::string dll, HINSTANCE module);
 void init_sdk_modules();
-void fini_sdk_modules();
+	void fini_sdk_modules(bool graphics_stopped = false);
 
 }