[TC-221]: init template-backend-service (#1)

https://eva.avroid.tech/desk/cards?obj=Task:TC-221

Начальная версия сервиса-шаблона

Co-authored-by: Nadezhda <nadezhda.lavrentieva@avroid.team>
Reviewed-on: https://git.avroid.tech/Templates/template-backend-service/pulls/1
Reviewed-by: Victor Stratov <victor.stratov@avroid.tech>

tests/samples.py

@@ -0,0 +1,9 @@
+ACCOUNT_1 = {
+    "country_id": 1,
+    "iso_3166_code_alpha3": "RU",
+}
+
+ACCOUNT_2 = {
+    "country_id": 2,
+    "iso_3166_code_alpha3": "EN",
+}