Don't use ports and adapters for ImportGraph

It's never brought any value to have an abstraction for the
ImportGraph. So this removes the abstract class and then moves the
concretion to the application layer.

Author: seddonym

.importlinter

@@ -18,6 +18,6 @@ ignore_imports =
     ; is an object within grimp, rather than a module in its own right,
     ; so we ignore these imports here.
     grimp.adaptors.caching -> grimp
-    grimp.adaptors.graph -> grimp
+    grimp.application.graph -> grimp
     grimp.adaptors.filesystem -> grimp
     grimp.application.scanning -> grimp

src/grimp/__init__.py

@@ -1,6 +1,6 @@
 __version__ = "3.12"
 
-from .application.ports.graph import DetailedImport, ImportGraph, Import
+from .application.graph import DetailedImport, ImportGraph, Import
 from .domain.analysis import PackageDependency, Route
 from .domain.valueobjects import DirectImport, Module, Layer
 from .main import build_graph