feat: implement keyboard with arabic and syriac letters

This MR adds a virtual keyboard to the search page. The first commit add arabic keyboard only to test the behaviour of the simple-keyboard library. It also serves as first design draft with focus on functionality rather styling.

Steps:

• Go to /search.html
• Click the keyboard button on the right of search field
• An overlay with keyboard opens up
• You can switch between Arabic/Syriac layouts
• Click close button
• Open/close multiple times -> Input should not be overridden
• Search field should be focused "properly"

closes #65 (closed)