openapi: Render all responses of an operation.

Previously, one needed to specifying all the HTTP status
codes that we want to render along with the operation,
but the primary use case just needs the responses of
all the status codes, and not just one.

This commit modifies the Markdown extension to render
all the responses of all status codes of a specified
operation in a loop.

zerver/openapi/markdown_extension.py

@@ -451,14 +451,12 @@ class APICodeExamplesPreprocessor(Preprocessor):
                     language, options = parse_language_and_options(match.group(2))
                     function = match.group(3)
                     key = match.group(4)
-                    argument = match.group(6)
                     if self.api_url is None:
                         raise AssertionError("Cannot render curl API examples without API URL set.")
                     options["api_url"] = self.api_url
 
                     if key == "fixture":
-                        if argument:
-                            text = self.render_fixture(function, name=argument)
+                        text = self.render_fixture(function)
                     elif key == "example":
                         path, method = function.rsplit(":", 1)
                         if language in ADMIN_CONFIG_LANGUAGES and check_requires_administrator(
@@ -484,9 +482,9 @@ class APICodeExamplesPreprocessor(Preprocessor):
                 done = True
         return lines
 
-    def render_fixture(self, function: str, name: str) -> List[str]:
+    def render_fixture(self, function: str) -> List[str]:
         path, method = function.rsplit(":", 1)
-        return generate_openapi_fixture(path, method, name)
+        return generate_openapi_fixture(path, method)
 
 
 class APIDescriptionPreprocessor(Preprocessor):