Rebuild columns styles using the SCSS from Gridstack 8.x

Hi @Panchuk!
I've rebuilt the columns' styles. I left only the default 12 columns and created CSS styles for 24 columns. I used the suggestion by the gridstack.js team for that. (https://github.com/gridstack/gridstack.js#custom-columns-css)
Also, the libraries and buildForm() method were updated.

Please, review the MR. Thanks.

Thanks, @SmovS for your contribution.
MR looks good, I've merged it.

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