[12574] Implement spells for Mimiron encounter

Spell effects: 64402, 65346, 63027, 63667, 63681, 64841, 63382
Drop spells 63820, 64425, 64620, 64398, 64426, 64621 because they will be handled by script
[12575] Update for Mimiron encounter spells

Add targets limit and spell effect for spell 64623
Remove target limit for spells 63387 and 64531 because they proved to be wrong
Fix mistake for spell 65346; thanks LilleCarl for pointing. This will be handled by script
Finally add positive exception for spell 64402