Enable "sticky" features when changing FW type

I remember earlier we had the ability to keep the currently enabled features enabled and the disabled one disabled when switching to another firmware. Now the features get overwritten by the defaults when I switch to another FW.
For example, let us say I want to build a Pixhawk1-bdshot FW. I may not need all the features so I decide to start off from the -1M version and build on top of it by adding /removing features as removing features from the 2MB version will be more time consuming. But there is no button that keeps my current selections active as I switch but this used to exist a few months earlier.
I request to bring this back.
Thanks

Start by tracing the firmware-type switching flow and where the current feature selections are stored or replaced. Reproduce the switch from the 1M firmware to another firmware, then verify that enabled features remain enabled and disabled features remain disabled after switching.

Written by the indexing model from the issue text.