Build: migrate most grunt tasks off of grunt (3.x)

Build: migrate most grunt tasks off of grunt (3.x)

Close gh-5330

- lint
- npmcopy
- build, minify, and process for distribution.
- new custom build command using yargs
- compare size of minified/gzip built files
- pretest scripts, including qunit-fixture, babel transpilation, and npmcopy
- node smoke tests
- promises aplus tests
- new watch task using nodemon, which runs `npm run build:all` on `src` changes.

Also:

- upgraded husky and added the new lint command
- updated lint config to use new "flat" config format.
	See https://eslint.org/docs/latest/use/configure/configuration-files-new
- Temporarily disabled one lint rule until flat config is
	supported by eslint-plugin-import.
	See https://github.com/import-js/eslint-plugin-import/issues/2556
- committed package-lock.json
- updated all test scripts to use the new build
- added an express test server that uses middleware-mockserver
	this can be used to run tests without karma
- build-all-variants is now build:all
- run pretest script in jenkins

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Co-authored-by: Michał Gołębiowski-Owczarek <m.goleb@gmail.com>