menu folder items unnecessarily capitalized + slow load each time

[tomholub]

(small) regression:

• menu items (folders) now take visibly longer to load
• it says INBOX instead of Inbox etc (had to adjust appium test for it)
  Will file another issue.

Originally posted by @tomholub in #985 (comment)

[tomholub]

There used to be caching mechanism for the folder names showing in the menu (stored in local db?). There still probably is, but one of our refactors must have broken it. Need to investigate why the menu items are not cached, currently seem to load from API on each menu open.

[tomholub]

No, I suppose that may be the cause of the issue.

I think it should probably get reloaded at least sometimes, but not every time we open menu.

It could open menu from cache, and then make an API call in background and if the response from API is different, re-render menu items while open.