feat(@angular-devkit/schematics): re-export core string helpers from schematics package

The string helpers are predominantly used within schematics that will already depend and import from
the `@angular-devkit/schematics` package. By re-exporting from `@angular-devkit/schematics`, the need
to directly depend and import `@angular-devkit/core` within a schematic can be reduced and in many
cases eliminated.

Author: clydin

goldens/public-api/angular_devkit/schematics/index.md

@@ -12,6 +12,7 @@ import { Observable } from 'rxjs';
 import { Path } from '@angular-devkit/core';
 import { PathFragment } from '@angular-devkit/core';
 import { schema } from '@angular-devkit/core';
+import { strings } from '@angular-devkit/core';
 import { Subject } from 'rxjs';
 import { Url } from 'url';
 import { virtualFs } from '@angular-devkit/core';
@@ -841,6 +842,8 @@ export function source(tree: Tree_2): Source;
 // @public (undocumented)
 const standardFormats: schema.SchemaFormat[];
 
+export { strings }
+
 // @public (undocumented)
 export interface TaskConfiguration<T = {}> {
     // (undocumented)

packages/angular_devkit/schematics/src/index.ts

@@ -6,6 +6,7 @@
  * found in the LICENSE file at https://angular.io/license
  */
 
+import { strings } from '@angular-devkit/core';
 import * as formats from './formats/index';
 import { FilePredicate, MergeStrategy, Tree as TreeInterface } from './tree/interface';
 import { branch, empty, merge, partition } from './tree/static';
@@ -33,8 +34,7 @@ export * from './engine/schematic';
 export * from './sink/dryrun';
 export * from './sink/host';
 export * from './sink/sink';
-export { formats };
-export { workflow };
+export { formats, strings, workflow };
 
 export interface TreeConstructor {
   empty(): TreeInterface;