Extension point for external files should include a DbControl also for unsaved new file items

[Nicklas Nordborg]

Consider the following similar code snippets:

File f = File.getNew(dc, directory);
f.setUrl(url, true);
f.saveItem(dc);

and

File f = File.getNew(dc, directory);
f.saveItem(dc);
f.setUrl(url, true);

and

File f = File.getById(dc, fileId);
f.setUrl(url, true);

The only difference is that the File.setUrl() method is called before or after saving the file. If there is a registered extension for the given url, the extension system will pass on the DbControl in the second and third cases but not in the first. I think the DbControl should always be passed on.

[Nicklas Nordborg]

(In [6513]) Fixes #1830: Extension point for external files should include a DbControl also for unsaved new file items