Create pipeline BotBuilder-JS-CI-node12-yaml

[BruceHaley]

...and normalize botbuilder-js-ci.yml.
The pipeline: https://fuselabs.visualstudio.com/SDK_v4/_build?definitionId=1008&_a=summary
This satisfies issue #2331.

[coveralls]

Pull Request Test Coverage Report for Build 144025

• 0 of 0 changed or added relevant lines in 0 files are covered.
• 9 unchanged lines in 2 files lost coverage.
• Overall coverage decreased (-0.07%) to 80.607%

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Files with Coverage Reduction	New Missed Lines	%
libraries/botframework-streaming/src/webSocket/webSocketTransport.ts	2	80.65%
libraries/botframework-streaming/src/webSocket/webSocketServer.ts	7	66.67%

Totals
Change from base Build 143855:	-0.07%
Covered Lines:	12979
Relevant Lines:	15377

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💛 - Coveralls

[stevengum]