adding vcap_services class from frontend (#89)

* adding vcap_services class from frontend

fsd_utils/toggles/vcap_services.py

@@ -0,0 +1,30 @@
+import json
+from dataclasses import dataclass
+
+
+@dataclass
+class VcapServices(object):
+
+    services: dict
+
+    @staticmethod
+    def from_env_json(json_string: str):
+        json_dict = dict(json.loads(json_string))
+        vcap_services = VcapServices(services=json_dict)
+        return vcap_services
+
+    def does_service_exist(self, service_key: str) -> bool:
+        return service_key in self.services.keys()
+
+    def get_service_by_name(self, group_key: str, name: str) -> dict:
+        service_group = self.services.get(group_key)
+        if service_group:
+            for service in service_group:
+                if service.get("name") == name:
+                    return service
+            raise Exception(f"Service name '{name}' not found")
+        raise Exception(f"Service group '{group_key}' not found")
+
+    def get_service_credentials_value(self, group_key: str, name: str, key: str):
+        service = self.get_service_by_name(group_key, name)
+        return service.get("credentials").get(key)