bridge_builtin_features: add beep via touch variable

bridge_builtin_features: add beep via touch variable

Add periodic beep option to one-touch recording by setting
the touch variable TOUCH_MONITOR_BEEP or
TOUCH_MIXMONITOR_BEEP to the desired interval in seconds.

If the interval is less than 5 seconds, a minimum of 5
seconds will be imposed.  If the interval is set to an
invalid value, it will default to 15 seconds.

A new test event PERIODIC_HOOK_ENABLED was added to the
func_periodic_hook hook_on function to indicate when
a hook is started.  This is so we can test that the touch
variable starts the hook as expected.

ASTERISK-30446

Change-Id: I800e494a789ba7a930bbdcd717e89d86040d6661