Improve type for just-clone to accept primitives too

[dumbmatter]

The TypeScript types for just-clone say that the input must be an object, but if you look at the code that's not true, it works fine with a primitive as well. So maybe the type should just be T rather than T extends object. This is what lodash uses for cloneDeep.

Alternatively all the primitives could be specified like T | number | string | ... but if T is good enough for lodash it's probably good enough here too.