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>

reporter/interfaces.py

@@ -0,0 +1,29 @@
+from abc import ABC, abstractmethod
+from contextlib import AbstractContextManager
+from typing import Any
+
+
+class Reporter(ABC):
+    """
+    Interface that supports storage of test artifacts in some reporting tool.
+    """
+
+    @abstractmethod
+    def step(self, name: str) -> AbstractContextManager:
+        """
+        Register a new step in test execution.
+
+        :param str name: Name of the step
+        :return: step context
+        """
+        pass
+
+    @abstractmethod
+    def attach(self, content: Any, file_name: str) -> None:
+        """
+        Attach specified content with given file name to the test report.
+
+        :param any name: content to attach. If not a string, it will be converted to a string.
+        :param str file_name: file name of attachment.
+        """
+        pass