Introduce a callback in `outputs::Outputs` that calls on every `wl_output.done`, and a dummy consumer in `ui_manager`.
This is sufficient to detect display height changes.
Parameters fudged appropriately to preserve dimensions from the original design targting Librem5:
- 720×1440 results in 420px height, via max finger size
- 1440×720 results in 360px height, via not exceeding half the display
In absence of physical dimensions, a pixel is assumed to measure half the size as on the Librem5, and then shrunk by the current display scale factor.This gives the ability to test in nested phoc at selected scale factors like before (2x being most accurate), and keeps the right size in QEMU.
The manager is used for sizing the layer surface. It promises never to exceed half the output height.
The selection of the current layout is not being done here, leading to worse behaviour in 1:1 scaling.
In the future, it could be used for sizing the keyboard itself and the suggestion box, as well as decide which layout to use, because layouts should have some sizing hints.
Without handling transform, the surface was created with the wrong size on rotated displays, causing flicker before the .configure event arrived. With, it will attempt to set the right size from the start.
