Have the preview service reload components when files in projects change

When QML or JS files are edited the changed files need to be pushed to the preview debug service, which will then reload the QML engine, using the new files. This task is about the plumbing on the Qt Creator side:

• figure out if the changed file is valid QML/JS
• determine the URL(s) it is available from in the target application
• push the file through the debug connection