Add typography classes to pfe-styles

[starryeyez024]

• the typography classes from the redhat-theme should live in pfe-styles, for example:

.pfe-headline-xxl {
  font-family: "RedHatDisplay", "Overpass", Overpass, Helvetica, Arial, sans-serif;
  font-family: var(--pfe-theme--font-family--heading, "RedHatDisplay", "Overpass", Overpass, Helvetica, Arial, sans-serif);
  font-size: calc(1.92  * 18px);
  font-size: var(--pfe-theme--font-size--xxl, calc(1.92  * var(--pfe-theme--base--heading-lg, 25px)));
  line-height: 1.2;
  line-height: var(--pfe-theme--line-height--xxl, 1.2);
  font-weight: 300;
  font-weight: var(--pfe-theme--font-weight--xxl, 300); }

[castastrophe]

Closing issue now that the linked PR was merged