Grid CSS: add offset

[NicolaIsotta]

1) Environment

• PrimeFaces version: 6.2
• Does it work on the newest released PrimeFaces version? Version? no 6.2
• Does it work on the newest sources in GitHub? (Build by source -> https://github.com/primefaces/primefaces/wiki/Building-From-Source) no
• Application server + version: all
• Affected browsers: all

2) Expected behavior

With the commit primefaces/primeng@ba14090 (which closed primefaces/primeng#3362 ), offset classes were added to the "new" grid CSS. It would be nice if the changes could be ported to primefaces too.

NB: primefaces/primeng#5144 changes could be ported too

[tandraschko]

@mertsincan Are there any plans to port it?

[melloware]

+1 on this.

[melloware]

Attaching this sample here to prove everything is working.
pf-grid.zip