Allow to use context menu and popup button for translate selected text

[vitonsky]

Motivation

Currently we have available options as below

But user may want both - translate text by popup button and by click on context menu for selected text.

Changes

We have to improve current behavior:

• move an option "Context menu button" to another option "Enable translation with context menu" and implement behavior according to options
• add option "None"
• rename "Translation trigger" option to "Action for text selection", add option "None" there and rename exists options to "Instant translation" and "Show button for translation"