feat: Export common SCSS variables as CSS variables

[xitij2000]

Description

This commit exports commonly-used SCSS variables as CSS variables as well so
that they can be used by MFEs, or other consumers of Paragon, without needing to
be rebuilt each time a theme variable changes.

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[tecoholic]

Suggested change

	--png-spacer-#{$size}: #{$length};
	--pgn-spacer-#{$size}: #{$length};

[xitij2000]

This is no longer needed with the most recent changes.

[tecoholic]

@xitij2000 👍 with the linting issue fixed

• I tested this: I built this, added the output css into an independent html file, and used the CSS values using var()
• I read through the code
• I checked for accessibility issues - NA
• Includes documentation

[codecov]

Codecov Report

Base: 90.40% // Head: 90.40% // No change to project coverage 👍

Coverage data is based on head (136c94e) compared to base (2e7847f).
Patch has no changes to coverable lines.

Additional details and impacted files

@@           Coverage Diff           @@
##           master    #1620   +/-   ##
=======================================
  Coverage   90.40%   90.40%           
=======================================
  Files         208      208           
  Lines        3534     3534           
  Branches      824      824           
=======================================
  Hits         3195     3195           
  Misses        324      324           
  Partials       15       15           

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[natabene]

@xitij2000 Thank you for the contribution. Is this ready for our review?

[xitij2000]

@xitij2000 Thank you for the contribution. Is this ready for our review?

Yes. Thanks!

[mphilbrick211]

Hi @xitij2000 - is this PR still needed? If so, I can get it reviewed. Looks like it fell off the radar.

[xitij2000]

Hi @xitij2000 - is this PR still needed? If so, I can get it reviewed. Looks like it fell off the radar.

I think this work is overshadowed by the design tokens work going on. I will close this PR for now, and reopen if needed.

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