Support "Assemble them all" trajectory generation from CAD

asp/src/usecases/generate_world.py

@@ -0,0 +1,12 @@
+import os
+from helper.fs import FS
+
+class SdfGenerateWorldUseCase:
+    def call(assembly:str) -> str:
+        world = FS.readFile(os.path.dirname(os.path.realpath(__file__))
+                           + '/../../mocks/sdf/world.sdf')
+        beginWorld = world[0:world.find('</world') - 1]
+        endWorld = world[world.find('</world') - 1: world.__len__()]
+        
+        
+        return beginWorld + assembly + endWorld