AIOG-T-51. TelegramObject property bot added

* property added
 * unit tests added
 * local import used to avoid circular reference

tests/test_api/test_types/test_telegram_object.py

@@ -0,0 +1,21 @@
+import pytest
+
+from aiogram import Bot
+from aiogram.api.types import TelegramObject
+
+
+class TestTelegramObject:
+    @pytest.fixture()
+    def context_cleanup(self):
+        yield
+        Bot.reset_current(self.__token)
+
+    @pytest.mark.usefixtures("context_cleanup")
+    def test_bot_property_positive(self):
+        self.__token = Bot.set_current(Bot("42:TEST"))
+
+        assert isinstance(TelegramObject().bot, Bot)
+
+    def test_bot_property_negative(self):
+        with pytest.raises(RuntimeError, match=r"Bot.set_current\(bot_instance\)"):
+            isinstance(TelegramObject().bot, Bot)