1. Read mux indices from modules_placed.yaml instead of manually calculating them
2. Add "power_switch" and "analog" fields to shuttle_index.json
3. Copy the power gate macros (tt_pg_vdd_1, tt_pg_vdd_2) into to tt_top directory
The commit date provides an easy method to compare two shuttle_index.json files and detect which of the files relates to a newer commit. This enables us to prevent a situation where an earlier shuttle_index overrides a later one.