port: refactor plugin interface to BotComponent class

[joshgummersall]

Step one of #3453

The unfortunate downside here is that we no longer have a "global" registry of keys and types. This will have to suffice in order to move forward on deprecating ComponentRegistrations in favor of BotComponents. Producing the registry would result in dependency cycles. We can perhaps revisit making this more type-safe in a future revision.

[coveralls]

Pull Request Test Coverage Report for Build 691490361

• 0 of 0 changed or added relevant lines in 0 files are covered.
• 10 unchanged lines in 2 files lost coverage.
• Overall coverage decreased (-0.06%) to 84.947%

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Files with Coverage Reduction	New Missed Lines	%
libraries/adaptive-expressions/src/triggerTrees/trigger.ts	2	61.63%
libraries/adaptive-expressions/src/triggerTrees/node.ts	8	91.7%

Totals
Change from base Build 691469957:	-0.06%
Covered Lines:	18906
Relevant Lines:	21185

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💛 - Coveralls

[stevengum]