Added fields to ChatMember (#340)

* Added fields to ChatMember
* Added ChatMemberStatus helper

tests/test_api/test_types/test_chat_member.py

@@ -0,0 +1,34 @@
+import pytest
+
+from aiogram.api.types import ChatMember, User
+
+user = User(id=42, is_bot=False, first_name="User", last_name=None)
+
+
+class TestChatMember:
+    @pytest.mark.parametrize(
+        "status,result",
+        [
+            ["administrator", True],
+            ["creator", True],
+            ["member", False]
+        ]
+    )
+    def test_is_chat_admin(self, status: str, result: bool):
+        chat_member = ChatMember(user=user, status=status)
+        assert chat_member.is_chat_admin == result
+
+    @pytest.mark.parametrize(
+        "status,result",
+        [
+            ["administrator", True],
+            ["creator", True],
+            ["member", True],
+            ["restricted", True],
+            ["kicked", False],
+            ["left", False]
+        ]
+    )
+    def test_is_chat_member(self, status: str, result: bool):
+        chat_member = ChatMember(user=user, status=status)
+        assert chat_member.is_chat_member == result