VSE: Python API: Deprecate sequence properties and replace with new ones

This PR adds new RNA properties that deprecate and replace any `sequence` property.
The old prooperties are still there and fully functional, but the description is changed
to indicate that these will be removed in the future and that the new properties should
be used instead.

| Deprecated property | Replacement property |
| --------------------------------- | ----------------------------------- |
| `context.active_sequence_strip` | `context.active_strip` |
| `context.selected_editable_sequences` | `context.selected_editable_strips` |
| `context.selected_sequences` | `context.selected_strips` |
| `context.sequences` | `context.strips` |
| `SequenceEditor.sequences` | `SequenceEditor.strips` |
| `SequenceEditor.sequences_all` |  `SequenceEditor.strips_all` |
| `MetaStrip.sequences` | `MetaStrip.strips` |

Previously, rna paths for animation data on strips started with `sequence_editor.sequences`.
This PRadds versioning for the rna paths to make sure to use
the new naming scheme. This does mean that in previous versions of blender,
the animations don't show but the data is not lost (even if the file is saved in the older version).

Also do some cleanup of existing python scripts inside the source to use the
new properties.

Part of #132963.

Pull Request: https://projects.blender.org/blender/blender/pulls/133156

scripts/startup/bl_operators/wm.py

@@ -2845,9 +2845,9 @@ class WM_OT_batch_rename(Operator):
                 return data_type_test
             if data_type == data_type_test:
                 data = (
-                    context.selected_sequences
+                    context.selected_strips
                     if only_selected else
-                    scene.sequence_editor.sequences_all,
+                    scene.sequence_editor.strips_all,
                     "name",
                     iface_("Strip(s)"),
                 )