ThreadMember exposes user notification settings

[Sanduhr32]

flags	integer	any user-thread settings, currently only used for notifications

> from ThreadMember docs

I somehow feel like the public api shouldn't expose a thread members thread notification setting to everyone.
It has virtually no use and considering discords api data limitation changes, this should not be possible.
its also not really documented.

I suggest removing the attribute flags from thread member objects, because it's only useful for clients itself and not for bots.

[ajpalkovic]

I think this is likely a misreading of the docs
notif settings are zero'd out before being sent to other people
if you are able to access someone else's notification settings, please file an issue along with repro steps and we'll take care of it