Refactor: move checks/lib into lib/ to avoid duplicate lib

Lets avoid the mistake of nixpkgs having multiple
libs

lib/test/default.nix

@@ -7,9 +7,12 @@ let
 
 in
 {
+  #
+  containerTest = import ./container-test.nix;
+  baseTest = import ./test-base.nix;
+  #
   flakeModules = clanLib.callLib ./flakeModules.nix { };
 
-  #
   minifyModule = ./minify.nix;
   sopsModule = ./sops.nix;
   # A function that returns an extension to runTest