`raise` -> `throw`

[cknitt]

For throwing exceptions, we have the function raise whose name was inherited from OCaml.

I would propose to rename it to throw in v12 to align it with JS.

[cknitt]

Should be easy to change as it is just an external definition in Pervasives.

However, for compatibility we can keep both in parallel for now, then deprecate raise at some point and eventually remove it at a later time.