feat(list): Add notifyAction adapter for action on list item.

[abhiomkar]

notifyAction adapter method is introduced to notify on user action including keyboard and mouse. This could've been notifySelected but the a list can also be a checkbox variant where it can have multiple selections and an action could also cause unselect.

BREAKING CHANGE: Removed adapter method followHref and used native anchor element behaviour to follow href on Enter & click. Components that use MDC List should use its new custom event.

Changes required for #3481

[mdc-web-bot]

All 691 screenshot tests passed for commit b39a6b1 vs. master! 💯🎉

[codecov-io]

Codecov Report

Merging #4144 into master will not change coverage.
The diff coverage is 100%.

@@           Coverage Diff           @@
##           master    #4144   +/-   ##
=======================================
  Coverage   98.58%   98.58%           
=======================================
  Files         127      127           
  Lines        5705     5705           
  Branches      762      762           
=======================================
  Hits         5624     5624           
  Misses         81       81

Impacted Files	Coverage Δ
packages/mdc-list/constants.js	100% <ø> (ø)	⬆️
packages/mdc-list/foundation.js	100% <100%> (ø)	⬆️
packages/mdc-list/index.js	98.47% <100%> (-0.03%)	⬇️

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[mdc-web-bot]

All 691 screenshot tests passed for commit 1d4f896 vs. master! 💯🎉

[mdc-web-bot]

All 691 screenshot tests passed for commit a7e8edd vs. master! 💯🎉

[mdc-web-bot]

All 691 screenshot tests passed for commit 5c93287 vs. master! 💯🎉

[mdc-web-bot]

All 758 screenshot tests passed for commit 20d069e vs. master! 💯🎉

[kfranqueiro]

LGTM, presuming tests pass now

[kfranqueiro]

PS: I think this should probably be considered a feat in the commit subject, along with the breaking change in the commit description.

[mdc-web-bot]

All 758 screenshot tests passed for commit f127152 vs. master! 💯🎉