This cleanup naming convention and code clarity. There
is no functional change.
- `elem_ranges` is changed to a `Map` to avoid relying on
`sel_data->drawn_index`.
- `select_draw_utils.cc` is merged with `select_engine.cc`
- `index_drawn_len` is renamed to `max_index_drawn_len`
- Remove the usage of `DrawData`
Rel #134690
Pull Request: https://projects.blender.org/blender/blender/pulls/134940
1b902e305c