CSS Library: Fix font faces being loaded from uswds

[micahchiang]

Description

On December 5th the design system team merged in a pull request to swap the import path of core stylesheets in vets-website from Formation to css-library. This change removed a reference to fonts managed in Formation, where USWDS v1 font-faces were imported directly into Formation's core.scss file. Without the presence of this Formation stylesheet, source sans pro fonts were no longer being picked up and included in vets-website's webpack build, which outputs assets to a folder named /generated.

Temporarily, a fonts.scss has been added to vets-website which patches necessary fonts and re-adds them to the /generated folder in a build that gets published from vets-website to S3.

Additionally, css-library makes use of this stylesheet which declares some font-faces and imports others from uswds-fonts. We need to verify how we're using this, as it seems like the imported uswds font-faces aren't actually being used.

Considerations

• We may not be using @use properly. All @use does is namespace imports, which is distinctly different than what @import does. In order to use the font faces provided by uswds, we probably need to declare font faces and give them a value of whatever we get from uswds.
• The core issue here is that source sans pro ttf fonts were not being added to /generated, and they need to be. Their presence there can be verified by checking the /generated folder in the build directory of vets-website.
• More context can be found in this slack thread

Tasks

• Ensure font-faces are being used properly in css-library/base/fonts.scss when using @use
• Test changes locally in vets-website using verdaccio. We should be able to publish an updated css-library version to verdaccio that includes changes to /base/fonts.scss. A successful test here is the removal of this vets-website stylesheet and fonts still be added as expected to vets-website/build/localhost/generated
• Once fonts are successfully being generated given the above, write a follow up task to remove the fonts.scss stylesheet from vets-website. This can be done during the css-library release in which these changes get published to vets-website

Acceptance Criteria

• above tasks have been completed