[FIXED] [Mage][Arcane] Arcane orb on hit AM procs

[Ligma]

WoW Freakz spell link: Arcane Orb

Bug description: Arcane orb works almost like frost spec frozen orb. It has a chance to grant missile proc on cast and every time it deals damage. Currently it only generates procs on cast but never on mob hits. Same problem applies to legendary shoulder orb.
In BFA it no longer has a chance to generate AM procs on mob hits because the system was changed to clearcasting and bla bla.

Proof: https://youtube.com/watch?v=ST9qYaNRI6U:



A few examples:

1:38 gains AM proc in mid cast of arcane blast when orb hits hatecoil crusher.
6:20 has 1 AM proc, casts orb gains 2nd proc, when orb reaches mobs gains 3rd AM proc, slow down video if needed but it should be pretty clear just from the UI element of AM procs.
9:48 has 1 AM proc, casts orb, starts casting arcane blast and gains another AM proc mid cast when orb reaches mobs and hits them


This video shows legendary shoulder orb behaving the same way
https://youtube.com/watch?v=Z2ChmlkjeP4:



2:57 Has no am procs, casts barrage and shoulder orb procs, gains 2 missile procs instantly and 1 more when orb hits dummy, all while he is still in global cooldown lock. Slow down video if needed.
3:24 this one is more clear, same situation as previous example but he doesnt gain any AM procs except when the shoulder orb hits dummy while he is in mid cast of arcane blast. Cant be more clear than this.

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Freakz proof that it only procs on cast but never on hit. My missile proc chance on spells is 27%
https://youtube.com/watch?v=KDgvT8_Evks: