Keep an existing field's weight value the same

Issue:
When fundraiser_webform updates the webform field settings it sets the weight value to one computed in an earlier functions calculation, overriding the configured value. This is good for when a form is initially being created, but causes issues for existing forms.

Replicate:
Change the order of fundraiser fields within the same fieldest. Save the form and see that the fields have gone back to the previous placements.

Fix:
In _fundraiser_webform_update_component for an existing field set the $component['weight'] to the one configured for that field.