JIT: Enable fgOptimizeRelationalComparisonWithCasts for EQ/NE

[BoyBaykiller]

We were previously only calling that for GT_LT, GT_LE, GT_GE, GT_GT.
Example:

bool Test(uint a)
{
    return (ulong)(a) == uint.MaxValue;
}

;; ------ BASE
G_M000_IG02:
       mov      eax, edx
       mov      ecx, 0xFFFFFFFF
       cmp      rax, rcx
       sete     al
       movzx    rax, al

;; ------ DIFF
G_M60965_IG02:
       cmp      edx, -1
       sete     al
       movzx    rax, al

Currently includes #127883 which should be merged first.

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