Reduce diff between FAWE PaperweightAdapter and WE PaperweightAdapter classes

[SirYwell]

To make porting easier, we should try to minimize the diff between WE PaperweightAdapter and our changes on top of it.

That means:

• Figure out the reason for our changes
• If they improve something and apply to WE too, consider upstreaming
• If they do not improve something, get rid of them
• If they are specific to FAWE, try moving them to the PaperweightFaweAdapter subclass
• Otherwise, properly document why this change is needed

This can be done in multiple steps, looking at small parts only.