Move custom directives as close as possible to modules that use them

As part of converting the Channel Manager to Angular the second step is to sanitize the current code base. For this we want to move custom directives as close as possible to modules that use them:

1. illegalCharacters → channel/page/actions
2. scrollToIf → channel/sitemenueditor
3. stopPropagation → channel/sitemenueditor

The complete plan can be found here: https://docs.google.com/document/d/1RoGCnJSBXrvP0kdd0jGLzWNd6Cbv1ucCpbo0YLNUN5c