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

src/ifcopenshell-python/ifcopenshell/api/georeference/add_georeferencing.py

@@ -0,0 +1,20 @@
+class Usecase:
+    def __init__(self, file, settings=None):
+        self.file = file
+
+    def execute(self):
+        source_crs = None
+        for context in self.file.by_type("IfcGeometricRepresentationContext", include_subtypes=False):
+            if context.ContextType == "Model":
+                source_crs = context
+                break
+        if not source_crs:
+            return
+        projected_crs = self.file.create_entity("IfcProjectedCRS", **{"Name": ""})
+        self.file.create_entity("IfcMapConversion", **{
+            "SourceCRS": source_crs,
+            "TargetCRS": projected_crs,
+            "Eastings": 0,
+            "Northings": 0,
+            "OrthogonalHeight": 0,
+        })