BaseEq should probably always sort its operands

[langston-barrett]

Many instances of BaseEq in What4.Expr.Builder sort their operands:

what4/what4/src/What4/Expr/Builder.hs

Line 1770 in 038e948

sbMakeExpr sym $ BaseEq (SR.semiRingBase sr) (min xr yr) (max xr yr)

what4/what4/src/What4/Expr/Builder.hs

Line 1773 in 038e948

sbMakeExpr sym $ BaseEq (SR.semiRingBase sr) (min x y) (max x y)

what4/what4/src/What4/Expr/Builder.hs

Line 2081 in 038e948

_ -> sbMakeExpr sym $ BaseEq BaseBoolRepr (min x y) (max x y)

what4/what4/src/What4/Expr/Builder.hs

Line 2759 in 038e948

sbMakeExpr sym $ BaseEq (SR.semiRingBase sr) (min xr yr) (max xr yr)

what4/what4/src/What4/Expr/Builder.hs

Line 2768 in 038e948

-> sbMakeExpr sym $ BaseEq (BaseBVRepr (bvWidth x)) (min x y) (max x y)

But some don't:

what4/what4/src/What4/Expr/Builder.hs

Line 3235 in 038e948

= sbMakeExpr sym $ BaseEq (BaseStringRepr (stringInfo x)) x y

what4/what4/src/What4/Expr/Builder.hs

Line 3474 in 038e948

sbMakeExpr sym $! BaseEq (exprType x) x y

what4/what4/src/What4/Expr/Builder.hs

Line 3791 in 038e948

| otherwise = floatIEEELogicBinOp (BaseEq (exprType x)) sym x y

The latter probably should too. In fact, we should probably have a helper

baseEq :: BaseTypeRepr t -> Expr t -> Expr t -> Expr t
baseEq t x y = BaseEq t (min x y) (max x y)

with some Haddocks about why this is generally a good idea.

[langston-barrett]

This baseEq helper should also probably encapsulate the following common rewrite:

what4/what4/src/What4/Expr/Builder.hs

Lines 2066 to 2067 in 038e948

	| x == y
	= return (truePred sym)