rename all remaining packages to internal/ (#12418)

This is to ensure that there are no projects
that try to import `minio/minio/pkg` into
their own repo. Any such common packages should
go to `https://github.com/minio/pkg`

internal/s3select/json/testdata/12.json

@@ -0,0 +1,5 @@
+{
+    "a": 1
+}{
+    "b": 2
+}