libweston: Add surface-fps log scope

Add a 'surface-fps' log scope which will print out the current
frames per second for all surfaces on the fly.

This introduces a simple configuration in weston.ini:

[core]
surface-fps=true

The default value is false, so no behavioral change is introduced.
3 jobs for enable-surface-fps in 1 minute and 44 seconds (queued for 1 second)
latest
Status Job ID Name Coverage
  Container Prep
passed #3288362
container_prep

00:00:57

 
  Build
passed #3288363
build-native-meson-default-options

00:00:47

passed #3288364
build-native-meson-no-gl-renderer

00:00:38