qa: Task to emulate network delay and packet drop between two given hosts

qa: Task to emulate network delay and packet drop between two given hosts

The task uses netem to emulate wide area network delay.
Provides three different configurable options.
1. standard delay: Constant delay with +/- 5ms jitter with normal distribution as default.
2. variable delay: To provide a delay between two given min-max range in milliseconds.
3. packet drop: Toggles packet drop and recovery in regular interval.

Useful in simulating network delays between two clusters while testing
rgw multisite and rbd mirroring configurations.

Signed-off-by: Shilpa Jagannath <smanjara@redhat.com>