First attempt at ripping out agnostic code into ifcopenshell.api namespace. See #1399.

src/ifcopenshell-python/ifcopenshell/api/context/data.py

@@ -0,0 +1,27 @@
+class Data:
+    is_loaded = False
+    contexts = {}
+
+    @classmethod
+    def purge(cls):
+        cls.is_loaded = False
+        cls.contexts = {}
+
+    @classmethod
+    def load(cls, file):
+        if not file:
+            return
+        cls.contexts = {}
+        for context in file.by_type("IfcGeometricRepresentationContext", include_subtypes=False):
+            subcontexts = {}
+            for subcontext in context.HasSubContexts:
+                subcontexts[int(subcontext.id())] = {
+                    "ContextType": subcontext.ContextType,
+                    "ContextIdentifier": subcontext.ContextIdentifier,
+                    "TargetView": subcontext.TargetView,
+                }
+            cls.contexts[int(context.id())] = {
+                "ContextType": context.ContextType,
+                "HasSubContexts": subcontexts
+            }
+        cls.is_loaded = True