[RISCV] Fold (X & -4096) == 0 -> (X >> 12) == 0 (#154233)

This is a more general form of the recently added isel pattern
(seteq (i64 (and GPR:$rs1, 0x8000000000000000)), 0)
  -> (XORI (i64 (SRLI GPR:$rs1, 63)), 1)

We can use a shift right for any AND mask that is a negated power
of 2. But for every other constant we need to use seqz instead of
xori. I don't think there is a benefit to xori over seqz as neither
are compressible.

We already do this transform from target independent code when the setcc
constant is a non-zero subset of the AND mask that is not a legal icmp
immediate.

I don't believe any of these patterns comparing MSBs to 0 are
canonical according to InstCombine. The canonical form is (X < 4096).
I'm curious if these appear during SelectionDAG and if so, how.

My goal here was just to remove the special case isel patterns.

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