Dynamically update schedule from Python

Adds some test cases that show how injection properties in Opm::Schedule
can be dynamically modified from Python.

python/opm2/simulators/__init__.py

@@ -0,0 +1,12 @@
+# Instead of having the pybind11 extension module, e.g.
+#   simulators.cpython-310-x86_64-linux-gnu.so  located
+#   directly in the opm2 directory, we create a package (sub
+#   directory) with the same name and place it there.
+#   In this way we can do (if needed in the future)
+#
+#  from opm.simulators import BlackOilSimulator, FoamSimulator, PurePythonUtils, ...
+#
+#  where FoamSimulator and PurePythonUtils does not currently exists,
+#  but could be possible future extensions..
+#
+from .simulators import BlackOilSimulator