Migrate diagrams from old repo laa-hosting-diagrams

[davidkelliott]

There are a lot of plantuml drawings already hosted here https://github.com/ministryofjustice/laa-hosting-diagrams
Some time could probably be saved by migrating some of these rather than redoing everything (I know for example the CCMS diagrams are up to date as I did them recently).

Also I think the old repo should be archived and a link to the new repo created so people know to no longer use it.