Introduce exporters_list_created hook to new export code (#1978)

* Introduce exporters_list_created hook for new export code

* Fix hook and argument name

qt/aqt/import_export/exporting.py

@@ -55,6 +55,7 @@ class ExportDialog(QDialog):
             NoteCsvExporter,
             CardCsvExporter,
         ]
+        gui_hooks.exporters_list_did_initialize(self.exporter_classes)
         self.frm.format.insertItems(
             0, [f"{e.name()} (.{e.extension})" for e in self.exporter_classes]
         )

qt/tools/genhooks_gui.py

@@ -19,7 +19,7 @@ prefix = """\
 
 from __future__ import annotations
 
-from typing import Any, Callable, Sequence, Literal
+from typing import Any, Callable, Sequence, Literal, Type
 
 import anki
 import aqt
@@ -856,6 +856,15 @@ gui_hooks.webview_did_inject_style_into_page.append(mytest)
         args=["legacy_exporter: anki.exporting.Exporter"],
         doc="""Called after collection and deck exports performed by legacy exporters.""",
     ),
+    Hook(
+        name="exporters_list_did_initialize",
+        args=["exporters: list[Type[aqt.import_export.exporting.Exporter]]"],
+        doc="""Called after the list of exporter classes is created.
+
+        Allows you to register custom exporters and/or replace existing ones by
+        modifying the exporter list.
+        """,
+    ),
     # Dialog Manager
     ###################
     Hook(