make executable requires xcode for macos

[margarita-v]

macOs Big Sur, M1 If XCode is not installed, command make executable will return error:

swift build --configuration release
error: terminated(72): /usr/bin/xcrun --sdk macosx --find xctest output:
    xcrun: error: unable to find utility "xctest", not a developer tool or in PATH
    
make: *** [release_build] Error 1

And the fix requires XCode installation. It would be nice if XCode installation would not be required for a simple command launch. It will make the whole SurfGen usage much more simple for those who don't use XCode at all, and the installation of such large IDE could be avoided. xctest dependency could be a possible reason which requires macOS users to install XCode.