[ci no changelog needed]
[Task link](https://www.pivotaltracker.com/story/show/182955595)
This PR implements variable column widths in the new Grid View component. We need this feature to quickly implement various parts of the UI, including the breadcrumbs panel of the component browser.
There are two ways to change the width of the specific column:
1. "From the outside", using the `set_column_width` endpoint of the Grid View
2. "From the inside", using the `override_column_width` endpoint of the EntryFrp.
Both ways work similarly, but the latter is helpful for our breadcrumbs implementation, as it allows for entry to decide on the width of the column by its content.
See the screencast with three grid views. The top-left one has every even column shrunk by GridView API. Every grid view has a second column extended by EntryFrp API.
https://user-images.githubusercontent.com/6566674/185060985-7b7df076-c659-41fa-977a-22875493f8d4.mp4
* Creating a new node with the (+) button (#3278)
[The Task](https://www.pivotaltracker.com/story/show/180887253)
A new (+) button on the left-bottom corner appeared. It may be clicked to open searcher in the middle of the scene, as an alternative to tab key.
https://user-images.githubusercontent.com/3919101/154514279-7972ed6a-0203-47cb-9a09-82dba948cf2f.mp4
* The window_control_buttons::common was extracted to separate crate `ensogl-component-button` almost without change.
* This includes a severe refactoring of adding nodes in general in the Graph Editor. The whole responsibility of adding new nodes (and starting their editing) was moved to Graph Editor - the Project View only reacts for GE events to show searcher properly.
* The status bar was moved from the bottom-left corner to the middle-top of the scene. It does not collide with (+) button, and plays "notification" role anyway.
* The `interface` debug scene was buggy. The problem was with one expression's span-tree. When I replaced it, the scene works.
* I've removed "new searcher" API, as it is completely outdated.
* I've changed code owners of integration tests to GUI team, as it is the team writing mostly the integration tests (int rust)
* Fix regression #181528359
* Add docs & remove unused function
* Fix & enable native Rust tests
* Fix formatting
Co-authored-by: Adam Obuchowicz <adam.obuchowicz@enso.org>
Co-authored-by: mergify[bot] <37929162+mergify[bot]@users.noreply.github.com>
