[AD] Wrap new Layer around selected layer (as a group) + Convert Group to Layers and visa versa

[Friksel]

Hi, I like the feature to select layers and group them and for some usecases that is great, because you can easily select those layers at once always.

But a lot of time I want to group layers, but not with a group, but as children of a new Layer object (instead of a Group object).
This is because Layers still have the ability to select children inside from within the viewport, while Groups can't do that.

I find myself converting groups to layers and back sometimes, because for one usecase I like to be able to select all sublayers, while sometimes it's better to use all 'as one' and want to have it grouped.

Right now converting between groups and layers isn't possible, so we need to add a new layer and drag all groupchildren inside and remove the group. A feature in the contextmenu to convert a Group to a Layer (as a group) would be very welcome. And also visa versa.