refactor(checkbox): Add Jasmine test for checkbox foundation.

[joyzhong]

• Add checkbox foundation test using Jasmine framework (converted from existing Mocha test). Does not delete Mocha test yet; this will be done in a follow-up PR.
• Set up Karma config such that npm run test:jasmineunit runs Karma/Jasmine unit tests, npm run test:mochaunit runs Karma/Mocha unit tests, and npm run test:unit runs both.
• Set up code coverage via karma-typescript/istanbul. Thresholds are lowered for now since Jasmine tests do not cover component tests, which were increasing the coverage percentage.

[codecov-io]

Codecov Report

Merging #5299 into master will decrease coverage by 0.32%.
The diff coverage is 88.23%.

@@            Coverage Diff            @@
##           master   #5299      +/-   ##
=========================================
- Coverage   98.63%   98.3%   -0.33%     
=========================================
  Files         122     162      +40     
  Lines        6000    6311     +311     
  Branches      772     866      +94     
=========================================
+ Hits         5918    6204     +286     
- Misses         81     106      +25     
  Partials        1       1

Impacted Files	Coverage Δ
testing/helpers/setup.ts	100% <100%> (ø)
testing/helpers/foundation.ts	87.23% <87.23%> (ø)
packages/mdc-dom/events.ts	90.9% <0%> (-9.1%)	⬇️
packages/mdc-ripple/util.ts	82.35% <0%> (-7.65%)	⬇️
packages/mdc-auto-init/index.ts	92% <0%> (-3.84%)	⬇️
packages/mdc-base/component.ts	93.33% <0%> (-3.1%)	⬇️
packages/mdc-top-app-bar/component.ts	98.5% <0%> (-1.5%)	⬇️
packages/mdc-drawer/component.ts	98.7% <0%> (-1.3%)	⬇️
packages/mdc-chips/chip-set/component.ts	97.4% <0%> (-1.29%)	⬇️
packages/mdc-tab-bar/foundation.ts	98.89% <0%> (-1.11%)	⬇️
... and 53 more

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[mdc-web-bot]

All 731 screenshot tests passed for commit 89fd463 vs. master! 💯🎉

[mdc-web-bot]

All 731 screenshot tests passed for commit e8fe73d vs. master! 💯🎉

[mdc-web-bot]

All 731 screenshot tests passed for commit 37977e3 vs. master! 💯🎉

[mdc-web-bot]

All 731 screenshot tests passed for commit f1accc0 vs. master! 💯🎉

[mdc-web-bot]

All 731 screenshot tests passed for commit 4997bd0 vs. master! 💯🎉

[abhiomkar]

LGTM!

[mdc-web-bot]

All 731 screenshot tests passed for commit 18e505a vs. master! 💯🎉

[mdc-web-bot]

All 731 screenshot tests passed for commit 43b81f4 vs. master! 💯🎉

[mdc-web-bot]

All 731 screenshot tests passed for commit e67d884 vs. master! 💯🎉

[mdc-web-bot]

All 731 screenshot tests passed for commit 032a1ba vs. master! 💯🎉

[mdc-web-bot]

All 731 screenshot tests passed for commit feb7d1d vs. master! 💯🎉

[mdc-web-bot]

All 731 screenshot tests passed for commit 6c08dca vs. master! 💯🎉

[mdc-web-bot]

All 731 screenshot tests passed for commit 6929207 vs. master! 💯🎉

[mdc-web-bot]

All 731 screenshot tests passed for commit 406d532 vs. master! 💯🎉

[mdc-web-bot]

All 731 screenshot tests passed for commit 7d2631d vs. master! 💯🎉

[mdc-web-bot]

All 731 screenshot tests passed for commit ef328ba vs. master! 💯🎉