Add support for nextjs Edge runtime

[BowlingX]

This is just a rough draft.

I think a better approach would be to use the export map to import different implementation.
e.g.

import { parseEnv } from "znv/node";
import { parseEnv } from "znv/next-edge";

The default could just point to the node implementation (to make it backwards compatible).
The easiest would possibly to make parseEnv a factory that allows to pass the reportErrors function.

[BowlingX]

The reason I had to add babel here is that ts-jest does not support the cts extension.
See kulshekhar/ts-jest#3996

[BowlingX]

Right now it's clumsy and I think not all runtimes can be detected properly, so it's better to just use export maps.