Allow exporting .stl to .jcad (#604)

* Allow exporting .stl to .jcad

* [pre-commit.ci] auto fixes from pre-commit.com hooks

for more information, see https://pre-commit.ci

---------

Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>

Author: martinRenou

python/jupytercad_core/jupytercad_core/handlers.py

@@ -28,7 +28,10 @@ def post(self):
                     visible=True,
                     shape="Part::Any",
                     parameters=dict(
-                        Content=file_content, Type=str(Path(Path(file_name).suffix[1:]))
+                        Content=file_content,
+                        Type=str(Path(Path(file_name).suffix[1:])),
+                        Color="#808080",
+                        Placement=dict(Position=[0, 0, 0], Axis=[0, 0, 1], Angle=0),
                     ),
                 )
             ],

python/jupytercad_core/src/stlplugin/model.ts

@@ -60,6 +60,7 @@ export class JupyterCadStlDoc extends JupyterCadDoc {
   }
 
   editable = false;
+  toJcadEndpoint = 'jupytercad/export';
 
   private _sourceObserver = (events: Y.YEvent<any>[]): void => {
     const changes: Array<{