Add operator for carryless multiply

[Validark]

Since #9631 was accepted, we are expecting a @mulCarryless builtin to be added to the language to support carryless multiplication. However, after further consideration and thought, I think this is something that can be well-expressed with a new operator instead. I think *^ is a good candidate, because another name for carryless multiplication is XOR multiplication. So this proposal is to add an operator instead.

fn prefixXOR(bitmask: anytype) @TypeOf(bitmask) {
    const all_ones = std.math.maxInt(@TypeOf(bitmask)) + std.math.minInt(@TypeOf(bitmask));
    return bitmask *^ all_ones;
}

By introducing a specific operator for carryless multiplication, Zig can provide a clear and concise syntax for expressing this operation. I think this operation deserves a seat at the table with the other arithmetic and bitwise operators, and I would like to see more people come up with new use-cases for it (recently I wrote an article on how you can use the prefixXOR operation to isolate every other bit in a bitmask). I am excited to hear the verdict on this proposal.