Revamp dockerfile for office-ui-fabric to reduce noise (#40147)
Revamp dockerfile for office-ui-fabric to reduce noise (#40147)

* Revamp dockerfile for office-ui-fabric to reduce noise and better handle recent changes to project structure

* Revert baseline change so it can be in the normal update, use node 12 since its LTS
kitsonk/TypeScript,microsoft/TypeScript,microsoft/TypeScript,kitsonk/TypeScript,SaschaNaz/TypeScript,Microsoft/TypeScript,microsoft/TypeScript,weswigham/TypeScript,SaschaNaz/TypeScript,kitsonk/TypeScript,weswigham/TypeScript,kpreisser/TypeScript,kpreisser/TypeScript,SaschaNaz/TypeScript,SaschaNaz/TypeScript,RyanCavanaugh/TypeScript,weswigham/TypeScript,RyanCavanaugh/TypeScript,Microsoft/TypeScript,kpreisser/TypeScript,Microsoft/TypeScript,RyanCavanaugh/TypeScript