Support simplification of `Contraint` objects

[Boyan-MILANOV]

We would really benefit from being able to simplify constraint patterns usually generated by conditional branches, such as:

(ITE[0==ITE[ecx_init<0x3](0x1, ITE[0==(0xfffffffd+ecx_init)](0x1,0))](0,0x1) != 0)

# The pattern here is
ITE[cond](0,1) != 0  ---> !cond