Add support for bitwise shift functions

[martint]

Presto currently supports bitwise functions and/or/xor/not. We should add support for bitwise left and right shift.

We need to consider how the function may or may not be sensitive to the length of the data type. From the original issue (prestodb/presto#4028):

Function that has tricky overflow issue:

BITWISE_LSH(7, 2, 4) = 12 -- treat 7 as a 4-bit signed number and left shift by 2,
                          -- truncate overflow

Function that are inherently sensitive to width of numbers:

BITWISE_LRSH(-8, 2, 5) = 6 -- treat -8 as a 5-bit signed number and lsh by 2

[martint]

Additionally, we need to think about the following scenarios:

• How does it behave for different types: TINYINT, SMALLINT, INTEGER, BIGINT?
• How does it behave with respect to implicit casts?

Naming-wise, we may want to call them bitwise_left_shift and bitwise_right_shift

[martint]

I think what we want are the following functions for each t in [TINYINT, SMALLINT, INTEGER, BIGINT]

bitwise_left_shift(value::t, bits::integer) :: t
bitwise_right_shift(value::t, bits::integer) :: t
bitwise_right_shift_signed(value::t, bits::integer) :: t

That would make the functions consistent with the implementations of shift operators for various types in traditional programming languages and databases that support shift operators. For each of the types in the list above, the values are interpreted as 2s complement signed 8-bit, 16-bit, 32-bit and 64-bit numbers, respectively. The _signed variant of right shift preserves the sign of the number (similar to >> in Java).

@prestosql/maintainers, @Lewuathe, thoughts?

[Lewuathe]

@martint
I think having multiple dedicated functions for each type is a good idea. That would make the interface clearer.

But _shift_arithmetic seems to be straightforward instead of _shift_signed so that we can make it explicit that the function is for the arithmetic right shift.

bitwise_left_shift(value::t, bits::integer) :: t
bitwise_right_shift(value::t, bits::integer) :: t
bitwise_right_shift_arithmetic(value::t, bits::integer) :: t

[martint]

The issue I have with arithmetic is that it's not immediately obvious to me that it means "extend sign". But it may be clear to others.

[martint]

In any case, let's go with this plan. We can finalize the name later.