I18n: Add message extraction regexes for node socket declarations

The node socket declarations use the `N_()` macro to extract the name
and description of the socket.

This is quite redundant because since the syntax is always the same,
the extraction can be done automatically from the Python translation
module using regexes.

Four new regexes are introduced in bl_i18n_utils.settings:
- one extracts contextless messages from `add_input()` and
  `add_output()`, the basic socket declarations with the names;
- one does the same, but for those sockets which declare a context
  through `.translation_context()`;
- one extracts descriptions and error messages;
- one extracts geometry nodes field inputs.

In addition to making the code simpler and more legible, this change
extracts a few dozen messages which were not tagged with the proper
macro.

scripts/modules/bl_i18n_utils/settings.py

@@ -256,6 +256,21 @@ PYGETTEXT_KEYWORDS = (() +
     tuple(("{}\\((?:[^,]+,){{2}}\\s*" + _msg_re + r"\s*(?:\)|,)").format(it)
           for it in ("modifier_subpanel_register", "gpencil_modifier_subpanel_register")) +
 
+    # Node socket declarations: contextless names
+    tuple((r"\.{}<decl::.*?>\(\s*" + _msg_re + r"(?:,[^),]+)*\s*\)").format(it)
+          for it in ("add_input", "add_output")) +
+
+    # Node socket declarations: names with contexts
+    tuple((r"\.{}<decl::.*?>\(\s*" + _msg_re + r"[^;]*\.translation_context\(\s*" + _ctxt_re + r"\s*\)").format(it)
+          for it in ("add_input", "add_output")) +
+
+    # Node socket declarations: description and error messages
+    tuple((r"\.{}\(\s*" + _msg_re + r"\s*\)").format(it)
+          for it in ("description", "error_message_add")) +
+
+    # Geometry Nodes field inputs
+    ((r"FieldInput\(CPPType::get<.*?>\(\),\s*" + _msg_re + r"\s*\)"),) +
+
     # bUnitDef unit names.
     # NOTE: regex is a bit more complex than it would need too. Since the actual
     # identifier (`B_UNIT_DEF_`) is at the end, if it's simpler/too general it