Propagate efficient `NDArray` scalar+tensor operations for `staticTensor`

[Iainmon]

Propagate efficient NDArray scalar+tensor operations such as

operator +(a: ndarray(?rank,?eltType),c: ?scalarType): ndarray(rank,eltType)
        where isNumericType(scalarType) do
    return ndarray.scalarMapOp("+",a,c);

up into the staticTensor and dynamicTensor world. Right now they are implemented as

// lib/StaticTensor.chpl
operator +(a: staticTensor(?rank,?eltType),c: ?scalarType): staticTensor(rank,eltType)
        where isNumericType(scalarType) {
    return a + staticTensor.valueLike(a,c : eltType);
}

Which is not the most efficient implementation, and should use the versions defined in NDArray.chpl.