Lock screen displays incorrectly in landscape orientation

Feature: https://source.puri.sm/Librem5/use-cases/issues/45

What problem did you encounter

The lock screen is incorrectly displayed in landscape orientation.

What is the current behaviour?

The lock screen is truncated in landscape orientation. The arrows are missing from the clock screen, and the bottom row of buttons are missing on the keypad screen.

What is the expected behaviour?

All the controls should be visible.

How to reproduce

• Open the top panel to access the Rotation slider.
• Enable it to switch to landscape orientation.
• Wait until the shell locks the screen.

Which version did you encounter the bug in?

• I Compiled it myself. If you compiled phosh from source please provide the git revision via e.g. by running git log -1 --pretty=oneline and pasting the output below.

• I used the precompiled Debian package (e.g. by running a prebuilt image). Please paste the output oof dpkg -s phosh below.

  Phosh Version: 0.0.3~567.gbp38a86e

What hardware are you running phosh on?

• amd64 qemu image
• Librem5 devkit
• nested compositor. If so please give the full command you start phosh with.
• other (please elaborte)