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/modules.h

@@ -0,0 +1,24 @@
+#pragma once
+
+#include <string>
+#include <vector>
+#include <windows.h>
+
+#include "sdk/include/spicesdk.h"
+
+namespace sdk {
+
+struct SdkModule {
+    std::string dll;
+    HINSTANCE module;
+};
+
+namespace modules {
+
+SPICE_SDK_STATUS_CODE get_module_info(const wchar_t *module_name, SPICE_SDK_MODULE_INFO *info);
+SPICE_SDK_STATUS_CODE get_plugin_directory(const std::vector<SdkModule> &registered_modules,
+    const void *plugin_address, wchar_t *buffer, uint32_t *size);
+
+}
+
+}