Integrate support for building with dependencies from vcpkg (#1880)

* Integrate support for building with dependencies from vcpkg

Configure the build using -DUSE_VCPKG=ON to use vcpkg. By default
recommended triplets targeting the OS versions official builds support
are used. You can opt out of this with -DUSE_RECOMMENDED_TRIPLETS=OFF.

* Add the vcpkg manifest

* Fetch vcpkg with FetchContent if we don't have it

* macOS cross compiling fixes

- can't use the x86_64 one as host triplet on arm64 because building Qt
  fails for whatever reason. Because of course it does :D
- vcpkg doesn't always like periods in triplet names so removed those

* x86_64 macOS should also use its recommended target when building arm64 builds

CMakeLists.txt

@@ -9,6 +9,11 @@ set(CMAKE_POLICY_DEFAULT_CMP0069 NEW)
 
 set(CMAKE_MODULE_PATH "${CMAKE_SOURCE_DIR}/cmake" ${CMAKE_MODULE_PATH})
 
+option(USE_VCPKG "Use vcpkg for dependency packages" OFF)
+if (USE_VCPKG)
+	include(ConfigureVcpkg)
+endif()
+
 project(melonDS
     VERSION 0.9.5
     DESCRIPTION "DS emulator, sorta"