Add the ability to generate random UUIDs for UUID cells

I propose adding functionality to the insert/update row contextual menu to allow generating random UUIDs for column values with the UUID type. This UI pattern is already present with e.g. timestampz:

<img width="1342" height="1238" alt="image" src=" />

We could add a edit icon in the same style conditional on the type of column being uuid and allow generating a random UUID to fill in the field. Happy to implement this myself if you guys approve of this request, btw :)