Capture mesh-catalog at feat/r4g (2246ccc4) with the templates its manifests name and its predefined.json, and lay the copy out as a repository's root

The catalogue's manifests moved their content into template files and fall back to predefined keys, so a copy of
module.json alone no longer passes the catalogue's own check; the bus's Dockerfile is gone from the catalogue.

testdata/beside/mesh-catalog/modules/model-usage/files/database.url

@@ -0,0 +1 @@
+postgresql://${bound:postgres-database:as}:${secret:postgres-database}@${bound:postgres-database:at}:${bound:postgres-database:port}/${bound:postgres-database:as}