Migration rules for the gap utility

[leagrdv]

The gap classes have changed to pixel sizes values. The goal of this ticket is to create migration rules for them.

The following classes need to be changed:

• gap-*
• column-gap-*
• row-gap-*

As well as all of their breakpoint siblings:

• *-sm-*
• *-md-*
• *-lg-*
• *-xl-*

Tasks

• Create a migration rule in our ESLint package that automatically replaces:
  • *-1 -> *-4
  • *-2 -> *-8
  • *-3 -> *-16
  • *-4 -> *-24
  • *-5 -> *-48
• Document the migration rule in the ESLint package
• Add tests for the rule
• Add information that we have an auto-migration in the migration guide
• Replace the classes in our own codebase