allow players to explicitly select default behavior

making this issue as a result of conversations around how to handle https://github.com/HarbourMasters/Shipwright/pull/5788

instead of having a tooltip saying
> In a Randomizer file, this defaults to on if this enhancement has never been changed.

for settings that default to `IS_RANDO`, it'd be good to have an explicit "default" option. something like
* default (on in randomizer files)
* always off
* always on
_____

next steps:
- [ ] make a list of settings that default to `IS_RANDO` but can't be explicitly set to `IS_RANDO` by players
- [ ] decide how we want to handle each of those
- keep the `IS_RANDO` default, add explicit `IS_RANDO` option?
- switch the setting to a shared default between rando and vanilla?
- something else?
- [ ] pr/land the changes