Investigate bitshifting beyond the size of SmallIntegers

[j4yk]

What does our bit-shifting primitive do in 32 bit if you do aSmallInteger << 48? Verify if Cog returns a LargePositiveInteger and that we return the same. There are probably test cases for this in the KernelTests-Numbers package.

@timfel told me that there used to be and could still be a lingering bug.

[krono]

Cog does

(4234 << 48) class "=> LargePositiveInteger"