Implement basic version of local shell

Also added two simple reporters that can be used by the shell to report command execution details.

Signed-off-by: Vladimir Domnich <v.domnich@yadro.com>

tests/helpers.py

@@ -0,0 +1,9 @@
+import traceback
+
+
+def format_error_details(error: Exception) -> str:
+    return "".join(traceback.format_exception(
+        etype=type(error),
+        value=error,
+        tb=error.__traceback__)
+    )