Parse assets from index.html (#127)

[mwistrand]

• Parse, copy, and hash <img src>, <script src>, and <link href>
  assets from src/index.html.
• Update the CSS rules to limit processing to the src/ and tests/
  directories.
• Ignore all assets imported from the assets/ directory.
• Change Dojo 2 to Dojo in README.md.
• Add the ico extension to the images rule.

This commit has already been merged to next, but now requires a separate PR to master.

[codecov]

Codecov Report

Merging #131 into master will decrease coverage by 0.04%.
The diff coverage is 25%.

@@            Coverage Diff             @@
##           master     #131      +/-   ##
==========================================
- Coverage   59.76%   59.71%   -0.05%     
==========================================
  Files           8        8              
  Lines         425      427       +2     
  Branches       94       92       -2     
==========================================
+ Hits          254      255       +1     
- Misses        171      172       +1

Impacted Files	Coverage Δ
src/base.config.ts	28.57% <25%> (+0.44%)	⬆️

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