* Guide: Split router module in guide.
Now we have: DMP, UMP and Router module.
* Add a glossary entry for what used to be called Router
* Extract DMP
* Extract UMP
* Extract HRMP
* Switch over to new modules
* Router: goodbye sweet prince
* Link to messaging overview for details.
* Update missed rococo and test runtimes.
* Commit destroyed by rebase changes
* Don't deprecate Router but rather make it a meta-project
Co-authored-by: Bernhard Schuster <bernhard@ahoi.io>
* Fix typos suggestion
Co-authored-by: Bernhard Schuster <bernhard@ahoi.io>
* Fix repetition in the impl guide
* Clarify that processed_downward_messages has the u32 type
* Remove the router subdir.
* Deabbreviate DMP,UMP,HRMP
Co-authored-by: Bernhard Schuster <bernhard@ahoi.io>