TSLint → ESLint (#21006)

* Alphabetized tslint and tsconfig files

* Optimized tsconfig files

* Optimized editorconfig & prettier config files

… to reduce redundancy

* Switched to @grafana/tsconfig

… and:
* de-duped options
* removed options with default values

* Fixed nasty issue with types for nested slate-react

* Replaced TSLint with ESLint

* TSLint disables → ESLint disables

… also JSHint removals, which haven’t had an affect since it was replaced with TSLint.

* Compliances for ESLint, Prettier and TypeScript

* Updated lockfile

scripts/grunt/default_task.js

@@ -11,7 +11,7 @@ module.exports = function(grunt) {
   // prettier-ignore
   grunt.registerTask('test', [
     'sasslint',
-    'tslint',
+    'eslint',
     'typecheck',
     'exec:jest',
     'no-only-tests',
@@ -19,9 +19,9 @@ module.exports = function(grunt) {
   ]);
 
   // prettier-ignore
-  grunt.registerTask('tslint', [
-    'newer:exec:tslintPackages',
-    'newer:exec:tslintRoot'
+  grunt.registerTask('eslint', [
+    'newer:exec:eslintPackages',
+    'newer:exec:eslintRoot'
   ]);
 
   // prettier-ignore