Enable gofumpt extra rules

Commit b2f8a74d "clothed" the naked return as inflicted by gofumpt
v0.9.0. Since gofumpt v0.9.2 this rule was moved to "extra" category,
not enabled by default. The only other "extra" rule is to group adjacent
parameters with the same type, which also makes sense.

Enable gofumpt "extra" rules, and reformat the code accordingly.

Signed-off-by: Kir Kolyshkin <kolyshkin@gmail.com>

libcontainer/internal/userns/userns_maps_linux.go

@@ -39,7 +39,7 @@ func parseIdmapData(data []byte) (ms []configs.IDMap, err error) {
 // Do something equivalent to nsenter --user=<nsPath> cat <path>, but more
 // efficiently. Returns the contents of the requested file from within the user
 // namespace.
-func spawnUserNamespaceCat(nsPath string, path string) ([]byte, error) {
+func spawnUserNamespaceCat(nsPath, path string) ([]byte, error) {
 	rdr, wtr, err := os.Pipe()
 	if err != nil {
 		return nil, fmt.Errorf("create pipe for userns spawn failed: %w", err)