[WebUI] Input text prediction and input bar: Styling & behavior fixes

[caisq]

• Increase the spacing between the word suggestions and the main input bar, to reduce the chance of accidentally hitting one of the word suggestions when scanning the already-entered text. This involves a 20px increase in the overall height of the web app.
• Put Expand & Spell buttons at right (end) of InputTextPredicitonComponet
• Improve logic for auto-inserted spaces during suggestion selection