I18n: Extract many messages from ED_push_undo

This function is used to add undo steps. It includes a message, for
use in the Undo History menu. This label uses the "Operator" context
for translation.

This commit adds automatic extraction of two functions `ED_undo_push`
and `ED_undo_grouped_push`, as well as manual extraction for many
strings not declared in the function calls.

In order to extract those messages using the proper context, the
extraction logic had to be changed so that a custom context could be
specified. The regexes can now be either a pattern, or
a (ctxt_override, pattern) tuple.

Pull Request: https://projects.blender.org/blender/blender/pulls/147581

scripts/modules/bl_i18n_utils/settings.py

@@ -269,6 +269,11 @@ PYGETTEXT_KEYWORDS = (() +
                      "CTX_wm_operator_poll_msg_set", "WM_global_report", "WM_global_reportf",
                      "UI_but_disable")) +
 
+    # ED_undo_push() is used in Undo History menu and has the "Operator" context, same as operators.
+    tuple(PyGettextKeyword(("{}\\((?:[^\"',]+,)\\s*" + _msg_re + r"\s*(?:\))").format(it),
+                           context_override='BLT_I18NCONTEXT_OPERATOR_DEFAULT')
+          for it in ("ED_undo_push", "ED_undo_grouped_push")) +
+
     # bmesh operator errors
     tuple(PyGettextKeyword(("{}\\((?:[^\"',]+,){{3}}\\s*" + _msg_re + r"\s*\)").format(it))
           for it in ("BMO_error_raise",)) +