libweston: Add frame commit frame rate counting

This is a continuation of work from
https://gitlab.freedesktop.org/wayland/weston/-/merge_requests/24



This patch adds a surface callback frame rate counter to the scene-graph
debug scope.

The timer interval is set by default to 1 second. This use a timer to
periodically compute the current frame callback commits in that interval
as the surface frame rate per timer interval.  Note that is solely based on
wl_surface::commit call.

Together with this, this patch also adds perfetto counter that stores
the same computed frame rate. This means the counter will be updated on
the next interval timer when the timer is armed/fired such that that
perfetto drawings will show up in a window period of time (interval).

Helpful to identify what frame rates clients achieve to debug
performance issues as to provide an objective common group. Using the
debug-scope aggregates all surfaces at the same place. This is not based
on the GPU whatsoever so it can also work on SHM type of buffers.

Signed-off-by: Marius Vlad <marius.vlad@collabora.com>
Signed-off-by: Changwoo Cho <changwoo.cho@lge.com>