[IMP] webservice_server_env: expose new OAuth2 options to server env

The webservice module gained new OAuth2 configuration fields (the token
request method, the client authentication method, and the custom
Authorization header name and value). These are now also manageable
through server environment configuration files, like the other
webservice fields.

Author: ivantodorovich

webservice_server_env/models/webservice_backend.py

@@ -29,6 +29,10 @@ def _server_env_fields(self):
             "oauth2_authorization_url": {},
             "oauth2_token_url": {},
             "oauth2_audience": {},
+            "oauth2_token_method": {},
+            "oauth2_client_auth_method": {},
+            "oauth2_client_auth_header": {},
+            "oauth2_client_auth_value": {},
         }
         webservice_fields.update(base_fields)
         return webservice_fields

webservice_server_env/tests/test_oauth2.py

@@ -104,6 +104,10 @@ def test_oauth2_flow_compute_with_ui(self):
                     ws_form.api_key_header = "Test Api Key Header"
                 if auth_type == "oauth2":
                     ws_form.oauth2_flow = oauth2_flow
+                    # ``oauth2_client_auth_method`` is only shown (and drives the
+                    # visibility of the client id/secret) for the backend flow.
+                    if oauth2_flow == "backend_application":
+                        ws_form.oauth2_client_auth_method = "client_secret_basic"
                     ws_form.oauth2_clientid = "Test Client ID"
                     ws_form.oauth2_client_secret = "Test Client Secret"
                     ws_form.oauth2_token_url = f"{url}oauth2/token"
@@ -122,6 +126,8 @@ def test_oauth2_flow_compute_with_ui(self):
                 ws_form.auth_type = new_auth_type
                 if new_auth_type == "oauth2":
                     ws_form.oauth2_flow = oauth2_flow
+                    if oauth2_flow == "backend_application":
+                        ws_form.oauth2_client_auth_method = "client_secret_basic"
                     ws_form.oauth2_clientid = "Test Client ID"
                     ws_form.oauth2_client_secret = "Test Client Secret"
                     ws_form.oauth2_token_url = f"{url}oauth2/token"