BsColConfig constructor
Creates a BsColConfig with optional spans for each breakpoint.
Implementation
const BsColConfig({
this.xs, // < 576px (Standard / mobile)
this.sm, // >= 576px
this.md, // >= 768px
this.lg, // >= 992px
this.xl, // >= 1200px
this.xxl, // >= 1400px
});