Add search history to search bar

[Dominik7272]

Closes #768
This PR implements a client-side search history feature to the search bar.

Features

• Searches will be stored per-account and synced across devices
• Leaving the search bar empty will show 10 recent searches, pressing the "Show more" button shows 10 more
• stores a max of 50 searches
• disable search history and clear it in the settings

[po5]

Interesting, thank you!
Do you have screenshots of this feature?
I will test it out when I can, though it might take me a while.
I think this has a place in szurubooru and I'd like to merge it.

Nitpicks from a quick glance:
API requests should use uri.formatApiLink(), and calling require() within functions doesn't follow the rest of the project.
I can fix stuff up, it's fine.

[Dominik7272]

Thanks for the feedback, I'm really glad to hear you'd like to merge it.
Regarding the nitpicks: I've went ahead and pushed a commit to resolve both.

Here are some screenshots below showing the search history dropdown:

Less than 10 queries:

More than 10 queries:

Options in the Settings menu: