Adding dev-tool to the repo (#7872)

* Azure SDK dev-tool first pass

* [dev-tool] dev-tool dev-samples and fixes to all commands

* Nested command structure

* Better argument parsing, type-checking, and recursive command structure. Added support for running a single sample.

* Added dev-tool README

* [ai-text-analytics] Update package.json to use new script.

* Removed some development cruft

* prettier + eslint

* Quick fix to ParsedOptions type

* WIP

* Command framework improvements

* Basic unit-tests for package resolution.

* One more test, assorted changes

* README update

* Migrated all packages with sample code to use dev-tool

* Added dummy integration-test stub

* Added dummy integration-test stub for eslint plugin

* Added dummy integration-test:browser stubs

* Added dev-tool dependency to packages using it

* Corrected build:samples step in package.json

* WIP

* [dev-tool] ts-to-js command

* [dev-tool] leaf command test

* Fixed more deeply nested samples due to shared code