As title. This will help use the two independently from the other, which
will help in an upcoming deno doc PR where I need to parse the source
files with scope analysis.
This is the initial support for npm and node specifiers in `deno
compile`. The npm packages are included in the binary and read from it via
a virtual file system. This also supports the `--node-modules-dir` flag,
dependencies specified in a package.json, and npm binary commands (ex.
`deno compile --unstable npm:cowsay`)
Closes #16632
