Make filters, actions and display_rows extras internal

These three extras return values that exist for the HTML templates -
a Filters instance, an async function and markupsafe/sqlite3.Row data
- so requesting them on a .json page returned a 500 serialization
error, while the generated documentation and ?_extra=extras both
advertised them as API surface. They are now public=False: ignored
like any unknown name on JSON requests, omitted from the docs and the
extras list, and still resolved for the HTML view via the new
include_internal flag on ExtraRegistry.resolve().

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

docs/json_api.rst

@@ -425,9 +425,6 @@ The available table extras are listed below.
           }
         ]
 
-``display_rows``
-    Row data formatted for the HTML table display
-
 ``render_cell``
     Rendered HTML for each cell using the render_cell plugin hook
 
@@ -554,12 +551,6 @@ The available table extras are listed below.
 
         "9403e5"
 
-``actions``
-    Table or view actions made available by plugin hooks
-
-``filters``
-    Filters object used by the HTML table interface
-
 ``renderers``
     Alternative output renderers available for this table