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

.editorconfig

@@ -16,6 +16,9 @@ charset = utf-8
 trim_trailing_whitespace = true
 insert_final_newline = true
 
+[*.{js,ts,tsx,scss}]
+quote_type = single
+
 [*.md]
 trim_trailing_whitespace = false