[PSA Export] Select all bone groups if none were previously selected

This brings back the old behavior (before 1ac0870) where all groups
are selected by default.

io_scene_psk_psa/helpers.py

@@ -58,9 +58,13 @@ def get_nla_strips_in_timeframe(object, frame_min, frame_max) -> List[NlaStrip]:
 
 
 def populate_bone_group_list(armature_object: Object, bone_group_list: Iterable[BoneGroupListItem]) -> None:
+    has_selected_groups = any([g.is_selected for g in bone_group_list])
+    unassigned_group_is_selected, selected_assigned_group_names = True, []
+
+    if has_selected_groups:
         # Preserve group selections before clearing the list.
-    # We handle selections for the unassigned group separately to cover the edge
-    # case where there might be an actual group with 'Unassigned' as its name.
+        # We handle selections for the unassigned group separately to cover the edge case
+        # where there might be an actual group with 'Unassigned' as its name.
         unassigned_group_idx, unassigned_group_is_selected = next(iter([
             (i, g.is_selected) for i, g in enumerate(bone_group_list) if g.index == -1]), (-1, False))
 
@@ -83,7 +87,7 @@ def populate_bone_group_list(armature_object: Object, bone_group_list: Iterable[
             item.name = bone_group.name
             item.index = bone_group_index
             item.count = 0 if bone_group not in bone_group_counts else bone_group_counts[bone_group]
-            item.is_selected = bone_group.name in selected_assigned_group_names
+            item.is_selected = bone_group.name in selected_assigned_group_names if has_selected_groups else True
 
 
 def get_psa_sequence_name(action, should_use_original_sequence_name):