agent: Add BatchableTelemMixin

Adds an implementation as a mixin of the two methods specified by
IBatchableTelem.

monkey/infection_monkey/telemetry/batchable_telem_mixin.py

@@ -0,0 +1,22 @@
+from typing import Iterable
+
+from infection_monkey.telemetry.i_batchable_telem import IBatchableTelem
+
+
+class BatchableTelemMixin:
+    """
+    Implements the IBatchableTelem interface methods using a list.
+    """
+
+    @property
+    def _telemetry_entries(self):
+        if not hasattr(self, "_list"):
+            self._list = []
+
+        return self._list
+
+    def get_telemetry_entries(self) -> Iterable:
+        return self._telemetry_entries
+
+    def add_telemetry_to_batch(self, telemetry: IBatchableTelem):
+        self._telemetry_entries.extend(telemetry.get_telemetry_entries())