Make MiniTerminal to work on touch devices

On a few devices which doesn't have physical keyboards like phones and tablets, the container is ready to listen to key events but there is no keyboard popping up when we tap on the terminal area.

Expectation:
Tapping on the terminal area should pop up the keyboard on devices with no physical keyboard and the key events should be captured by the container of terminal.

Inspect the MiniTerminal implementation and its terminal-area event handling first. Verify the behavior on a phone or tablet: tapping the terminal should open the software keyboard, and the terminal container should receive the resulting key events.

Written by the indexing model from the issue text.