211 support font display for googlefonts

[dakebl]

This PR adds a fontDisplay option to the options object that can be used to add font-display to google fonts imports.

Resolves #211

[codecov-io]

Codecov Report

Merging #212 into master will increase coverage by 0.03%.
The diff coverage is 100%.

@@            Coverage Diff             @@
##           master     #212      +/-   ##
==========================================
+ Coverage   98.26%   98.29%   +0.03%     
==========================================
  Files          43       43              
  Lines         230      235       +5     
  Branches       17       18       +1     
==========================================
+ Hits          226      231       +5     
  Misses          4        4

Impacted Files	Coverage Δ
packages/react-typography/src/GoogleFont.js	100% <100%> (ø)	⬆️

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[i8ramin]

Hi. Any chance this will get merged in?