bitbake: cooker: read file watches on server idle

bitbake: cooker: read file watches on server idle

The inotify facility monitoring changes to the config files
could be overwhelmed by massive changes to the watched files
while server is running.

This patch adds verification the notification watches to the
server idle functions, in addition to the cooker updateCache
command which executes only infrequently, thus preventing
overflowing the notification buffer.

[YOCTO #7316]

(Bitbake rev: 996e663fd5c254292f44eca46f5fdc95af897f98)

(Bitbake rev: b44694b1efc7389536df2f901a8b70321edfeeba)

Signed-off-by: Alexandru DAMIAN <alexandru.damian@intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>