Continuation of work in 2e221de4ce, 249e4df110 and 3a907e7425.
Adds new tree-element classes for the scene-ID, scene collections, scene
objects, and the view layers base.
There is some more temporary stuff in here, which can be removed once we're
further along with the porting. Noted that in comments.
Continuation of work in 2e221de4ce and 249e4df110 .
This prepares things so we can start porting the individual ID types to
the new code design. I already added some code for library IDs, because
they need some special handling during construction, which I didn't want
to break.
The `AbstractTreeElement::isExpandValid()` check can be removed once
types were ported and can be assumed to have a proper `expand()`
implemenation.
Also makes `TreeElementGPencilLayer` `final` which I forgot in
e0442a955b.
Continuation of the work started with 249e4df110. After all display modes
were ported to this new design, this commit starts the (more complex) work on
the individual tree-element types. More concretely it ports animation
tree-elements (action data-blocks, drivers and NLA data).
The commit above explains motivations. In short, we need a better design that's
easier to reason about and better testable.
Changes done here are pretty straight forward and introduce similar class
hierarchy and building patterns as introduced for the display modes already.
I.e. an abstract base class, `AbstractTreeElement` with derived classes for the
concrete types, and a C-API with a switch to create the needed objects from a
type enum. The latter should be replacable with something nicer later on (RAII
based, and type-safer through meta-programming).
Each tree-element type has its own class, with an own header and source file
(okay some closely related types can share a header and source file, like the
NLA ones).
I added some further temporary bits for the transition to the new design, such
as the `TreeElement.type`. It should entirely replace `TreeElement` eventually,
just as `outliner_add_element()` should be quite small by then and easily
replacable by a `TreeBuilder` helper.
