fix: set font-display: swap

[roedoejet]

Ensures text is visible even if font is not yet loaded.

This might produce some layout shifts, but ultimately I think this is more accessible particularly on slower networks.

Originally from #9

[ty2k]

Thanks very much for the PR @roedoejet!

I will take this change request to our team for discussion and I'll do some testing on it to see what the implications might be (especially contrasting how this might affect content heavy web pages vs dense web application layouts).

On a related note, previously, we have had folks request things like System Font Stack, either instead of or as a fallback for BC Sans. This might be a thing where we have to work in concert with the B.C. Design System to give different guidance depending on the app context.