Build: migrate most grunt tasks off of grunt

Updated tasks include:

- 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 `rollup.watch` directly

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

Close gh-5318

dist/.eslintrc.json

@@ -1,41 +0,0 @@
-{
-	"root": true,
-
-	"parserOptions": {
-		"ecmaVersion": 5,
-		"sourceType": "script"
-	},
-
-	"globals": {
-		"define": false,
-		"module": true,
-		"Symbol": false
-	},
-
-	"overrides": [
-		{
-			"files": "jquery{,.slim}.min.js",
-
-			"parserOptions": {
-				"ecmaVersion": 5,
-				"sourceType": "script"
-			}
-		},
-
-		{
-			"files": "jquery{,.slim}.js",
-			"extends": "../.eslintrc-browser.json",
-
-			"rules": {
-
-				// That is okay for the built version
-				"no-multiple-empty-lines": "off",
-
-				// When custom compilation is used, the version string
-				// can get large. Accept that in the built version.
-				"max-len": "off",
-				"one-var": "off"
-			}
-		}
-	]
-}