Add command to target build (/dist) folder for Jest tests

[hchiufaire]

Addresses #57 (missing json file from package) and #58 (tests not targeting /dist build folder)

• Added the new jest-dist.config.js file that interprets all "src" in imports as "dist/src" during test execution
• Added 2 custom commands:
  1. yarn test-dist-skip-build to run tests using the new config file (to target /dist)
  2. yarn test-dist to build then execute yarn test-dist-skip-build
• Fixed issue when testing /dist folder, by including html-entities.json in both bundles
• CI now uses yarn test-dist-skip-build

Note that yarn test still targets dev files as usual

Running yarn test to target dev folder

Running yarn test-dist to rebuild + target dist folder (before fix)

Running yarn test-dist to rebuild + target dist folder (after fix)