CPM added and directory structure changed

Switch to using CPM package manager instead of vcpkg as its just a wrapper around cmake and makes things more simple.

Switch dependency from spdlog to fmt.

Changed the directory structure to match the setup recommended by GitLab

cmake/precompiled.cmake

@@ -0,0 +1,8 @@
+include_guard()
+
+function( target_precompiled_header _target _header _source )
+	if( MSVC )
+		set_target_properties( ${_target} PROPERTIES COMPILE_FLAGS "/Yu${_header}" )
+		set_source_files_properties( ${_source} PROPERTIES COMPILE_FLAGS "/Yc${_header}" )
+	endif()
+endfunction()