Add icons for themes

[smhigley]

Type: bug / feature

The following has been addressed in the PR:

• There is a related issue
• All code matches the style guide
• Unit or Functional tests are included in the PR

Description:

Adds themed icons for the base theme, and updates the available icon classes in src/common/styles.

[codecov]

Codecov Report

Merging #256 into master will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master     #256   +/-   ##
=======================================
  Coverage   98.95%   98.95%           
=======================================
  Files          24       24           
  Lines        1429     1429           
  Branches      413      413           
=======================================
  Hits         1414     1414           
  Partials       15       15

Impacted Files	Coverage Δ
src/combobox/ComboBox.ts	99.41% <ø> (ø)	⬆️

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[bitpshr]

Nice, this looks great.

[tomdye]

Only thought is that we might want to include any font files under the theme dir rather than limiting to the dojo theme, there will be others in the future.

[smhigley]

Do you think the other themes will use Material icons too? If we think that will be pretty standard, I'm also in favor of moving them to /themes/fonts. I do also want to make sure it's easy to drop themes into projects. Will the CLI handle copying the correct theme css + fonts, so users won't need to remember they need themes/fonts in addition to e.g. themes/dojo?

[smhigley]

I'm going to merge and close this PR. For now, let's leave the icons within the theme, and revisit when we have a second theme.