Fix gulp file + update npm dependencies for starterkit - Maybe gulp5 if possible

@smustgrave the gulp file is working fine, can you specify a gulp version update + what other functionality should we build ??

Going to work on today.

Updated all npm packages to latest version and even updated to gulp5

Since gulp styelint is still very behind I removed the linting from gulp and put straight into the npm scripts

Updated README with more clear steps and description of commands available to run.

Fixed gulp command for cleaning out asset folders, previously wasn't working at all and wasn't being called.

Passed pipeline.

Automatically closed - issue fixed for 2 weeks with no activity.