Replace all instances of old variables controlling global grid widths and breakpoints with Patternfly variables for more consistency of spacing between elements and behaviors

The console has many instances of old variables, $grid-float-breakpoint and $grid-gutter-width, controlling margins/padding and responsive breakpoints throughout the Admin and Dev Console. These do not provide spacing and behaviors consistent with Patternfly components which use their own variables, $pf-global-gutter-md, $pf-global-gutter, and $pf-global-breakpoint-{size}. By replacing these, the intent it to bring the console closer to a pure Patternfly structure and behavior, requiring less overrides and customizations.