Search form UX improvements

[thibaudcolas]

• Loading indicator
• Reset the field contents when closing the form
• Animate reveal of the results

[benebun]

Hope it's ok if I add another point here instead of its own ticket:

• Focus input field after clicking on the search icon

[lb-]

I also encountered the issue today where I expected the clicking of the search button to focus on the search field. Instead it requires a second click (tap on mobile) to focus on this.