Disable or hide downvote actions when instance does not have downvotes enabled

[hjiangsu]

Pull Request Description

This PR hides downvote buttons and disables downvote actions when an instance does not have downvotes enabled. The following changes have been added/tested:

• Swipe gestures for downvotes for both posts and comments will throw an error indicating the instance has disabled downvotes
• In the comfortable view, the downvote icon is hidden when downvotes are disabled
• The comment button action downvote button is hidden when downvotes are disabled
• The post page downvote action is disabled

Issue Being Fixed

Issue Number: #19

Screenshots / Recordings

Screenshots

Checklist

• Did you update CHANGELOG.md?
• Did you use localized strings where applicable?
• Did you add semanticLabels where applicable for accessibility? (N/A)

[micahmo]

The code looks good to me!

The only question I'd have is whether there's an inconsistency between hiding the button in some places and disabling it in others. I don't have a strong preference, but just wanted to mention it as a point of discussion. Otherwise, LGTM!

[hjiangsu]

Just noticed that I was missing logic for checking the downvote setting when we switch accounts, so I'll add that in first before merging it in

The only question I'd have is whether there's an inconsistency between hiding the button in some places and disabling it in others

I thought a bit about this too - I think hiding the buttons themselves make sense since that isn't an action that should be performed (in hindsight, maybe I can also just hide the downvote icon/value on the post too). However, for things like swipe gestures, I decided to keep the downvote action in and just show an error because the swipe gesture setting is somewhat of a "global" setting.

It might potentially cause some confusion if the user has accounts on different instances where the downvote is enabled/disabled, and the swipe gesture settings change when they switch between instances

[micahmo]

I think hiding the buttons themselves make sense since that isn't an action that should be performed (in hindsight, maybe I can also just hide the downvote icon/value on the post too).

Sounds good, that's what I was getting at. If we're going with hiding, we should be able to hide on the post too. I think it's a flex layout so hopefully everything should still look fine.

However, for things like swipe gestures, I decided to keep the downvote action in and just show an error because the swipe gesture setting is somewhat of a "global" setting.

Yep, totally agreed on the decision here here. My comment was less about swipe gestures.

[hjiangsu]

Alright, updated some logic to handle checking instance settings when adding/switching accounts, and also removed downvote on post page @micahmo

[micahmo]

LGTM!

Just a mental note that I will have to test this functionality with anonymous instances in #677.

EDIT: Well, duh, you can't vote at all if you're not logged in! Confirmed, these changes work fine with and don't conflict at all with #677.