Function get_capabilities_handler 

async fn get_capabilities_handler(
    __arg0: AuthenticatedClientRequest<Request>,
) -> ArminiusResponse<Response>

Handler for GET /_matrix/client/v3/capabilities (See https://spec.matrix.org/v1.18/client-server-api/#get_matrixclientv3capabilities).

Gets information about the server’s supported feature set and other relevant capabilities.