Loader: Allow to toggle default family filters between "include" or "exclude" filtering

[BigRoy]

Brief description

This implements #2516

It adds an extra boolean checkbox in Admin Settings for Family Filters to decide whether the filtering is to "include" what you've selected or to "exclude" what you've selected.

Like the label describes in settings it works like this:

• Include: show selected families by default. Hides others by default.
• Exclude: hide selected families by default. Shows others by default.

So on Exclude always all families will be enabled except for those selected in the filter. On Include, it behaves like before, only the families you select in settings are enabled by default in the Loader.

Screenshot

This is how it looks in Settings:

Testing notes:

👍 I tested it in Maya 2020 on both include and exclude mode and it worked as intended.

[iLLiCiTiT]

I would just reduce the texts. The label should be moved before the checkbox and should have just one line Include/Exclude selected families ..... I think the (OFF) and (ON) is not needed too.

[mkolar]

I agree with @iLLiCiTiT that Exclude / Include as a label would be enough. We're designing a way to include in -situ documentation for all possible settings, so this verbose approach will be obsolete hopefully soon.

[BigRoy]

Removed the description label and reduced the checkbox label to solely Exclude / Include with commit d5bae9c

It now looks like this: