[ember] refactor @ember/string types into their own package (#28791)

* [@types/ember__string] refactor types out of @types/ember, add additional tests

* [@ember/string] enable all TSLint rules

types/ember__string/ember__string-tests.ts

@@ -0,0 +1,33 @@
+import { dasherize, camelize, capitalize, classify, decamelize, htmlSafe, loc, underscore, w } from '@ember/string';
+
+dasherize(); // $ExpectError
+dasherize('blue man group'); // $ExpectType string
+dasherize('', ''); // $ExpectError
+
+camelize(); // $ExpectError
+camelize('blue man group'); // $ExpectType string
+camelize('', ''); // $ExpectError
+
+decamelize(); // $ExpectError
+decamelize('blue man group'); // $ExpectType string
+decamelize('', ''); // $ExpectError
+
+underscore(); // $ExpectError
+underscore('blue man group'); // $ExpectType string
+underscore('', ''); // $ExpectError
+
+w(); // $ExpectError
+w('blue man group'); // $ExpectType string[]
+w('', ''); // $ExpectError
+
+classify(); // $ExpectError
+classify('blue man group'); // $ExpectType string
+classify('', ''); // $ExpectError
+
+capitalize(); // $ExpectError
+capitalize('blue man group'); // $ExpectType string
+capitalize('', ''); // $ExpectError
+
+loc(); // $ExpectError
+loc("_Hello World");  // $ExpectType string
+loc("_Hello %@ %@", ["John", "Smith"]);  // $ExpectType string

types/ember__string/index.d.ts

@@ -0,0 +1,18 @@
+// Type definitions for @ember/string 3.0
+// Project: http://emberjs.com/
+// Definitions by: Mike North <https://github.com/mike-north>
+// Definitions: https://github.com/DefinitelyTyped/DefinitelyTyped
+// TypeScript Version: 2.8
+
+import Ember from 'ember';
+
+export const camelize: typeof Ember.String.camelize;
+export const capitalize: typeof Ember.String.capitalize;
+export const classify: typeof Ember.String.classify;
+export const dasherize: typeof Ember.String.dasherize;
+export const decamelize: typeof Ember.String.decamelize;
+export const htmlSafe: typeof Ember.String.htmlSafe;
+export const isHTMLSafe: typeof Ember.String.isHTMLSafe;
+export const loc: typeof Ember.String.loc;
+export const underscore: typeof Ember.String.underscore;
+export const w: typeof Ember.String.w;

types/ember__string/tsconfig.json

@@ -0,0 +1,28 @@
+{
+    "compilerOptions": {
+        "module": "commonjs",
+        "target": "es5",
+        "lib": [
+            "es6",
+            "dom"
+        ],
+        "noImplicitAny": true,
+        "noImplicitThis": true,
+        "strictNullChecks": true,
+        "strictFunctionTypes": true,
+        "baseUrl": "../",
+        "typeRoots": [
+            "../"
+        ],
+        "paths": {
+            "@ember/string": ["ember__string"]
+        },
+        "types": [],
+        "noEmit": true,
+        "forceConsistentCasingInFileNames": true
+    },
+    "files": [
+        "index.d.ts",
+        "ember__string-tests.ts"
+    ]
+}

types/ember__string/tslint.json

@@ -0,0 +1,4 @@
+{
+    "extends": "dtslint/dt.json",
+    "rules": {}
+}