Support "node:" prefix on node imports

Writing `import fs from “node:fs”` is exactly the same as `import fs from “node”`. It would be nice if the list of supported built-in nodejs modules (https://www.checklyhq.com/docs/runtimes/specs/#built-in-nodejs-modules) also supported the “node:“ version of the modules. I recently spent some time debugging why `import fs from “node:fs”` did not work, before realising that i had to write `import fs from “node”` for it to work.