build system updates and other fixes

add preset config
import qt
separate core and frontend

CMakeModules/DownloadExternals.cmake

@@ -0,0 +1,18 @@
+
+# This function downloads a binary library package from our external repo.
+# Params:
+#   remote_path: path to the file to download, relative to the remote repository root
+#   prefix_var: name of a variable which will be set with the path to the extracted contents
+function(download_bundled_external remote_path lib_name prefix_var)
+set(prefix "${CMAKE_BINARY_DIR}/externals/${lib_name}")
+if (NOT EXISTS "${prefix}")
+    message(STATUS "Downloading binaries for ${lib_name}...")
+    file(DOWNLOAD
+        https://github.com/citra-emu/ext-windows-bin/raw/master/${remote_path}${lib_name}.7z
+        "${CMAKE_BINARY_DIR}/externals/${lib_name}.7z" SHOW_PROGRESS)
+    execute_process(COMMAND ${CMAKE_COMMAND} -E tar xf "${CMAKE_BINARY_DIR}/externals/${lib_name}.7z"
+        WORKING_DIRECTORY "${CMAKE_BINARY_DIR}/externals")
+endif()
+message(STATUS "Using bundled binaries at ${prefix}")
+set(${prefix_var} "${prefix}" PARENT_SCOPE)
+endfunction()