feat(c10y): add url_preview_domain_explicit_allowlist

roles/custom/matrix-continuwuity/defaults/main.yml

@@ -199,6 +199,9 @@ matrix_continuwuity_config_ignore_messages_from_server_names: []
 # Controls the `url_preview_domain_contains_allowlist` setting.
 matrix_continuwuity_config_url_preview_domain_contains_allowlist: []
 
+# Controls the `url_preview_domain_explicit_allowlist` setting.
+matrix_continuwuity_config_url_preview_domain_explicit_allowlist: []
+
 # Additional environment variables to pass to the container.
 #
 # Environment variables take priority over settings in the configuration file.

roles/custom/matrix-continuwuity/templates/continuwuity.toml.j2

@@ -1319,7 +1319,7 @@ url_preview_domain_contains_allowlist = {{ matrix_continuwuity_config_url_previe
 # attack surface to your server, you are expected to be aware of the risks
 # by doing so.
 #
-#url_preview_domain_explicit_allowlist = []
+url_preview_domain_explicit_allowlist = {{ matrix_continuwuity_config_url_preview_domain_explicit_allowlist | to_json }}
 
 # Vector list of explicit domains not allowed to send requests to for URL
 # previews.