Only create DTS for css modules

[agubler]

Type: bug

The following has been addressed in the PR:

• There is a related issue
• All code has been formatted with prettier
• Unit or Functional tests are included in the PR
• schema.json has been updated appropriately

Description:

Ensure that definition files are not created imported standard css from the src directory. For example when importing variables.css into a css module this should be filtered out.

[codecov]

Codecov Report

Merging #354 into master will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master     #354   +/-   ##
=======================================
  Coverage   48.62%   48.62%           
=======================================
  Files          10       10           
  Lines         689      689           
  Branches      193      193           
=======================================
  Hits          335      335           
  Misses        354      354

Impacted Files	Coverage Δ
src/base.config.ts	19.65% <ø> (ø)	⬆️

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