[ci no changelog needed]
[Task link](https://www.pivotaltracker.com/story/show/181725003)
This PR implements a fully visible component group header while scrolling the group (using the ScrollArea).
The header moves in sync with scrolling movements (using new `set_header_pos` FRP input), so it looks like the component group is scrolled. ScrollArea masks the "scrolled" entries above the header. This design allows a fully visible header even though our renderer doesn't support nested layers masking yet.
The screencast:
https://user-images.githubusercontent.com/6566674/168320360-2c2017b2-0ef5-42ce-9c79-82b9641c1d73.mp4
The most recent one, with the updated demo scene from develop:
https://user-images.githubusercontent.com/6566674/168555268-8552c4b0-f887-4388-89a1-e65ddf668be6.mp4
# Important Notes
- I fixed the API of the list view so now it supports non-hardcoded scene layers (previously it did not). I also believe it was implemented incorrectly.
- I've found a [pretty weird bug](https://www.pivotaltracker.com/story/show/182193824): the component group inside the ScrollArea is invisible unless I add some arbitrary shape to the scroll area content. I use a `transparent_circle` for this purpose in the demo scene. The bug is probably related to masking the sublayers, though I wasn't able to reproduce it properly on a simpler example.
- The selection box is removed from the demo scene as agreed with @farmaazon . The correct implementation has proven to be much harder than I expected, and we will implement another approach in a separate PR.
- I also modified the `shadow::Parameters` so that it uses `Var`s instead of plain values.
Parametrize the colors used in a Component Group view based on a single color passed to an FRP input.
Customizing the colors of a Component Group will be needed for the larger Component Group List panel. This customization will work as a visual hint for the User, helping them to distinguish different Component Groups in the panel. A single input color will be configured for every Component Group in the `package.yaml` file (see the Design Doc). Therefore, all shades of the color required by the Component Group view must be calculated from this single input color.
https://www.pivotaltracker.com/story/show/181725039
#### Visuals
The following screencast of the `component_group` debug scene shows how all required shades of color are calculated from a single input color. It also shows a new "dimmed" display mode of the Component Group. The debug scene does not support selecting entries in a "dimmed" Component Group, as this is not required by the Design Doc.
https://user-images.githubusercontent.com/273837/168074651-bf3d5ea5-99b0-4b69-9934-ad8565ffc54e.mov
The following is a screenshot of the Node Searcher, to demonstrate that it still works correctly:
<img width="623" alt="Screenshot 2022-05-09 at 17 13 01" src="https://user-images.githubusercontent.com/273837/167441109-e9a47b5a-45a2-4172-85ed-c593e43e02d6.png">
# Important Notes
- A new type `Params` was added in the `list_view::entry::Entry` trait. This was needed to allow passing FRP information to entries separately for every ListView instance.
- Note: `style_prefix` and `max_width_px` parameters of the `list_view::entry::Entry::new` function may get moved into the new `Params` type in the future. To save time, this was not attempted in this PR, as agreed with @farmaazon.
[ci no changelog needed]
* The List View component was refactored: it allows for hiding the internal selection widget, and exposes information where the widget should be placed. This allows us to create selection widget in component list panel, so it can be animated between component groups and sections.
* Fixed some warnings when checking WASM code.
* Adjusted the style of Component Group View a little, so it better reflects the design doc. Still not ideal, because the list_view has some weird design regarding padding, but I don't want to stuck in some bigger refactoring.
I will add a video in a few minutes.
# Important Notes
https://user-images.githubusercontent.com/3919101/165507826-60329f9e-7de3-4eb2-9271-292e45568cb2.mov
