Add multiply-high operation

[CatsAreFluffy]

Is your feature request related to a problem? Please describe. Currently, multiplying numbers with more than 24 bits is awkward, since you can only access the lower 24 bits of the full 48-bit result.

Describe the solution you'd like A new primitive operation that multiplies two numbers and returns the high half of the product.

Describe alternatives you've considered Waiting for native support for bigger numbers (and then asking for multiply-high for those since people will always need bigger numbers)

Additional context