Establish standards for custom events

[starryeyez024]

• Add base class for custom events
  • (Once we have adobe successfully seeing custom events, we can do more tests with moving content into the shadow DOM)
• Add documentation around naming and how-to for custom events within components

[starryeyez024]

@kylebuch8 please add details if you can, thanks!

[castastrophe]

I think bullet point #1 is addressed now

[castastrophe]

Addressed documentation here: #907