Improve parity handling of null in various operators

[ike709]

See the moved unit tests.

Summary:

• Bit shifting a LHS float and RHS null returns LHS as an integer
• Bit masking any float and null returns 0
• Bit XORing two nulls returns null
• Bit XORing a LHS float and RHS null returns LHS as an integer
• Bit XORing a LHS null and RHS float returns RHS as an integer
• Dividing LHS by null now returns LHS. Fixes Dividing a number by null doesn't provide the correct result #2148
• Fixed incorrect expected results in Division.dm