NDE: Add option for destructive filters

In discussion with @Jehan on IRC, there was concern that many users might prefer a destructive workflow over the new non-destructive one.

This can currently be done by merging the effects down after applying, but that is much more cumbersome than the current workflow.

To resolve this, a new checkbox is added to the bottom of the Filter Tool dialogue where users can toggle whether it will be applied destructively or non-destructively. Since it's part of the configuration, it will also be a persistent setting. The UI is likely the biggest sticking point, as the rest of the code is simple:

@Jehan Hi! Happy to make any GUI changes based on your or @aryeom's feedback.