Store program ID and expose it in Lua (#414)

src/core/memory.cpp

@@ -524,4 +524,14 @@ void Memory::copySharedFont(u8* pointer) {
 	auto fonts = cmrc::ConsoleFonts::get_filesystem();
 	auto font = fonts.open("CitraSharedFontUSRelocated.bin");
 	std::memcpy(pointer, font.begin(), font.size());
+}
+
+std::optional<u64> Memory::getProgramID() {
+	auto cxi = getCXI();
+
+	if (cxi) {
+		return cxi->programID;
+	}
+
+	return std::nullopt;
 }