build: configure the ng-dev caretaker check command

[josephperrott]

Create the configuration for the caretaker check command in the repo.

Makes available a check of the state of repository for caretakers via yarn ng-dev caretaker check

$ yarn ng-dev caretaker check
fatal: couldn't find remote ref g3
Github Tasks
  Merge Queue   0
  Triage Queue  3
  https://github.com/angular/components/issues?q=is:open%20label:%22needs%20triage%22
    - https://github.com/angular/components/issues/21593
    - https://github.com/angular/components/issues/21592
    - https://github.com/angular/components/issues/21583

Service Statuses
  Saucelabs ✅
  Npm       ✅
  CircleCi  ✅
  Github    ✅

CI
  releaseCandidate (11.1.x) ✅
  latest (11.0.x)           ✅
  next (master)             ✅

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