Option to disable voting on NSFW posts

On lemmy votes are public, and a lot of people are unaware of this, or miss click on a button and don't notice.

Could we add a option that either:
* Removes the voting buttons altogether
* Grays them out but they're disabled
* Clicking the vote button opens a confirmation prompt, that warns you something like "Warning, other users can see your votes"

I'm also concerned that regular users might not be aware of this, would it be reasonable to make this a default, and give the prompt a "don't remind me again" option?

This setting would be independent to the hiding or blurring NSFW options.

This is similar to issue #70
And PR #175