Spreadsheet: make active table lookup slightly more efficient

Move the active table to the front of the tables array, so that it
is easier to find in subsequent searches.

source/blender/editors/space_spreadsheet/space_spreadsheet.cc

@@ -451,6 +451,10 @@ static void spreadsheet_main_region_draw(const bContext *C, ARegion *region)
     table = spreadsheet_table_new(spreadsheet_table_id_copy(*active_table_id));
     spreadsheet_table_add(*sspreadsheet, table);
   }
+  if (table) {
+    /* Move to the front of the tables list to make it cheaper to find the table in future. */
+    spreadsheet_table_move_to_front(*sspreadsheet, *table);
+  }
 
   /* Update the last used time on the table. */
   if (table->last_used < sspreadsheet->table_use_clock || sspreadsheet->table_use_clock == 0) {

source/blender/editors/space_spreadsheet/spreadsheet_table.cc

@@ -345,4 +345,10 @@ void spreadsheet_table_remove_unused_columns(SpreadsheetTable &table)
       [](SpreadsheetColumn **column) { spreadsheet_column_free(*column); });
 }
 
+void spreadsheet_table_move_to_front(SpaceSpreadsheet &sspreadsheet, SpreadsheetTable &table)
+{
+  const int old_index = Span(sspreadsheet.tables, sspreadsheet.num_tables).first_index(&table);
+  dna::array::move_index(sspreadsheet.tables, sspreadsheet.num_tables, old_index, 0);
+}
+
 }  // namespace blender::ed::spreadsheet

source/blender/editors/space_spreadsheet/spreadsheet_table.hh

@@ -39,5 +39,6 @@ const SpreadsheetTable *spreadsheet_table_find(const SpaceSpreadsheet &sspreadsh
 void spreadsheet_table_add(SpaceSpreadsheet &sspreadsheet, SpreadsheetTable *table);
 void spreadsheet_table_remove_unused(SpaceSpreadsheet &sspreadsheet);
 void spreadsheet_table_remove_unused_columns(SpreadsheetTable &table);
+void spreadsheet_table_move_to_front(SpaceSpreadsheet &sspreadsheet, SpreadsheetTable &table);
 
 }  // namespace blender::ed::spreadsheet