[z2074] Wrap up the packet sending for a knockbacked player to WorldSession::SendKnockBack

Signed-off-by: Schmoozerd <schmoozerd@scriptdev2.com>

(based on commit [12111] - 493dfc2)

Signed-off-by: stfx <stfx@hotmail.de>

(based on commit [s1690] - c11211b)