Partial revert rust: add vlcrs-macros crate for module!{} macro, to fix authorship
Partial revert rust: add vlcrs-macros crate for module!{} macro
Partial revert of commit a1036731.
I completely messed up the authorship when importing the file. I though I had brought the file from Loïc Branstett merge request adding support in Rust but it seems I brought it from Vikram Kangotra's merge request adding WASM virtual machine in Rust (!5528).
Code on submodule handling was thus actually written by Vikram Kangotra.
Sorry for the trouble.