Formation Deprecation: Root font-size rem value migration

[micahchiang]

Description

After completing the discovery work on migrating the base font size,we have decided to migrate root font size globally.

There is some related work done already for this:

Confluence document:

• https://vfs.atlassian.net/wiki/spaces/DST/pages/2817130631/Discovery+Formation+base+font-size

Global approach code examples:

• Formation Global Updates: Update base font size and convert rem value veteran-facing-services-tools#987
• Formation Global Updates: Base font-size change from 10px to 16px vets-website#26606

Tasks

• migrate font size

Acceptance Criteria

• Font size has been migrated globally in vets-website, formation, and content build

[rmessina1010]

Created overrides files for Formation, and applied conversion utilities;

• note: still importing burbon from uswds, this is intentional, as it imports uswds utilities, but had no rem changes of note;
• pending: convert arbitrary px values

Ready for test/review