message: Add import support for five HLO unary ops.
  These ops are Abs, Ceil, IsFinite, Sign and Sqrt.
diff: @@ -525,12 +525,14 @@ StatusOr<mlir::Operation*> HloFunctionImporter::ImportInstruction(
  // broadcast dimensions are never added here because they don't exist as
  // part of the HLO instruction. They are only a convenience in the XLA
  // builder API.
  + NoAttributeCase(kAbs, AbsOp);
  NoAttributeCase(kAdd, AddOp);
  NoAttributeCase(kAfterAll, AfterAllOp);
  NoAttributeCase(kAnd, AndOp);
  NoAttributeCase(kAtan2, Atan2Op);
  NoAttributeCase(kBitcastConvert, BitcastConvertOp);
  NoAttributeCase(kConvert, ConvertOp);
  + NoAttributeCase(kCeil, CeilOp);
  NoAttributeCase(kClamp, ClampOp);
  NoAttributeCase(kComplex, ComplexOp);
  NoAttributeCase(kCos, CosOp);
  @@ -538,6 +540,7 @@ StatusOr<mlir::Operation*> HloFunctionImporter::ImportInstruction(
  NoAttributeCase(kExp, ExpOp);
  NoAttributeCase(kExpm1, Expm1Op);
  NoAttributeCase(kFloor, FloorOp);
  + NoAttributeCase(kIsFinite, IsFiniteOp);
  NoAttributeCase(kImag, ImagOp);
  NoAttributeCase(kLog, LogOp);
  NoAttributeCase(kLog1p, Log1pOp);
  @@ -562,7 +565,9 @@ StatusOr<mlir::Operation*> HloFunctionImporter::ImportInstruction(
  NoAttributeCase(kShiftLeft, ShiftLeftOp);
  NoAttributeCase(kShiftRightArithmetic, ShiftRightArithmeticOp);
  NoAttributeCase(kShiftRightLogical, ShiftRightLogicalOp);
  + NoAttributeCase(kSign, SignOp);
  NoAttributeCase(kSin, SinOp);
  + NoAttributeCase(kSqrt, SqrtOp);
  NoAttributeCase(kSubtract, SubOp);
  NoAttributeCase(kTanh, TanhOp);
  NoAttributeCase(kTuple, TupleOp);
  