The various paths where OPAM configuration files are stored.
Repository paths
Repository local path: $opam/repo/<name>
Return the repository config: $opam/repo/$repo/config
Packages folder: $opam/repo/$repo/packages
Remote package files: $remote/packages
Return the archive folder: $opam/repo/$repo/archives/
Return the upload folder for a given version: $opam/repo/$repo/upload/
Compiler files: $opam/repo/$repo/compilers/
Remote compiler files: $remote/compilers