Add entity position fields to allow user to position the entity

[NotStirred]

Closes #1325

I thought it fit better next to scale and head scale, as it's the position of the entity overall, not the position of any part

[Peregrine05]

So far, so good, except that when the selected entity is a lectern, the location controls apply only to the lectern, while all other controls apply to the book on the lectern.
I don't know if this is related, but when a lecten does not have a book, then the lectern does not get an entry in the Entities list.

[NotStirred]

I see the issue, lecterns are annoying

[Peregrine05]

The entity location controls now apply to not only the lectern, but also the book on top. Lecterns without books are still not listed in the entities list, however.

[NotStirred]

we should probably discuss what the behaviour should be
a lectern itself isn't poseable, it just has a position, and so shouldn't really be in the entity list. (like campfires, and other similar "entities")

Should we just have the book and remove the lectern?

[Peregrine05]

Further discussion about the previous comment took place on Discord.

[NotStirred]

Removed lectern changes, will push another PR fixing it

[NotStirred]

other PR is #1376

[Peregrine05]

From testing, everything is working as expected, except for the lectern bug, which will be fixed separately.