Fix: Ninja build command on Windows

The build commands for `ninja clean` on Windows were wrong - one had
the cmake executable duplicated and one was not using the correct
environment variable and also had missing quotes for paths that
contained spaces.  Tested working on with `make ninja clean` and
`make ninja clean release`.

Pull Request: https://projects.blender.org/blender/blender/pulls/128802

build_files/windows/configure_ninja.cmd

@@ -62,14 +62,14 @@ if NOT EXIST %BUILD_DIR%\nul (
 if "%MUST_CLEAN%"=="1" (
 	echo Cleaning %BUILD_DIR%
 	cd %BUILD_DIR%
-	%CMAKE% cmake --build . --config Clean
+	"%CMAKE%" --build . --config Clean
 )
 
 if NOT EXIST %BUILD_DIR%\build.ninja set MUST_CONFIGURE=1
 if "%NOBUILD%"=="1" set MUST_CONFIGURE=1
 
 if "%MUST_CONFIGURE%"=="1" (
-	cmake ^
+	"%CMAKE%" ^
 		%BUILD_CMAKE_ARGS% ^
 		-H%BLENDER_DIR% ^
 		-B%BUILD_DIR%