Implement hypot function

[ThatDesert]

Implement the hypot function in a similar manner to the already-existing arctan2 function.

Can be used for calculating magnitudes of resultant vectors given components (e.g. wind speed).

[sadielbartholomew]

Good idea. Thanks again Ollie. You'd be welcome to put in a PR yourself, but if you don't have the time/bandwidth then we will eventually get it added as a directly-supported operation.

[davidhassell]

Thanks, Ollie. Just to note that dask handily has a hypot method we can be used under the hood: https://docs.dask.org/en/stable/generated/dask.array.hypot.html