fix(@angular/cli): allow ng completion only outside of ng app folders

If an ng app folder was created with an older CLI version, then the ng CLI is upgraded globally,
one cannot perform `ng completion` INSIDE that app folder.
Thus it is advisable to only allow ng completion in places
such as shell start-up code, for which the completion is meant in the first place.
The completion call perfoemd in an ng app folder generated with an older version
issues a warning, which the shell cannot ignored, but tries to interpret as genuine
commands, and thus it fails miserably then and there.

The change constitute a breaking change, because previously `ng completion` could be
called from `everywhere`.

Author: catull

packages/@angular/cli/commands/completion.ts

@@ -43,7 +43,7 @@ const optsNg: string[] = [];
 const CompletionCommand = Command.extend({
   name: 'completion',
   description: 'Adds autocomplete functionality to `ng` commands and subcommands.',
-  works: 'everywhere',
+  works: 'outsideProject',
   availableOptions: [
     {
       name: 'all',