splitting lululxvi#1932 into an independent PR(deepxde)

Co-Authored-By: Chaoming Wang <[email protected]>

Author: Routhleck

deepxde/experimental/__init__.py

@@ -0,0 +1,21 @@
+__all__ = [
+    "callbacks",
+    "geometry",
+    "grad",
+    "icbc",
+    "metrics",
+    "nn",
+    "problem",
+    "utils",
+    "Trainer",
+]
+
+from . import callbacks
+from . import geometry
+from . import grad
+from . import icbc
+from . import metrics
+from . import nn
+from . import problem
+from . import utils
+from ._trainer import Trainer