Btrfs in installer menu missing

[ngaro]

Although it's easily doable with manual partitioning it would make a lot of sense to add a option for btrfs in the installer to automate it.
The best place would be in the menu where you can choose to use lvm.

Why it would be necessary:
Immediately in the welcome screen users recommended to configure snapshots with timeshift.
Timeshift gives you a rsync and btrfs option and rsync is actually something closer to a backup then to a snapshot.
Users that don't know anything about filesystems/partioning/... will not be able to use it

Suppose nobody has time for it, I wouldn't mind developing it myself and send a PR.
But in that case: Will it merged ? (Assuming it is tested and works fine)
(I am not going to spend time in coding something that is unwanted by the main developers and will never be merged...)