[ARM] Fold floating point select(binop) patterns

Similar to D84091 which added extra predicated folds for integer operations
using the identity element of the operation, this adds them for floating
point operations for the form `BinOp(x, select(p, y, Identity))`. They are
folded back to predicated versions of the operator, with fadd having the
identity -0.0, fsub using the identity 0.0 and fmul using 1.0.

Differential Revision: https://reviews.llvm.org/D113574