This is a counterpart for: https://github.com/NixOS/nixpkgs/pull/556611
When configPath is overridden, if wrapper supports the new appDataDir
argument, we pass configPath's absolute form to tell the app to look for
its datadir in the correct directory.
This will become necessary on macOS 27+ where Firefox that is not signed
by Mozilla has no access to its default datadir.
