[bookstack] Adds bookstack and cleans up a bunch of other files. Rewrites how mariadb instances are provisioned.

system/hosts/mcp/containers.nix

@@ -3,9 +3,11 @@
 {
   # Additional configuration
   imports = [
+    ./containers/bookstack.nix
     ./containers/gitea.nix
     ./containers/grafana.nix
     ./containers/jobhunt.nix
+    ./containers/mariadb.nix
     ./containers/nextcloud.nix
     ./containers/prometheus.nix
     ./containers/pocket-id.nix