Feature request: Allow defining a voice selection per language

[rpopov]

For multi-lingual use, when switching from reading in one language to another, version 1.73.0 imposes the following steps:

• Open the options menu
• Search for the appropriate voice
• (optional) Choose the appropriate speed.
  Even though it is easy to change the voice, one should remember which voice is most appropriate among all allowed. Some support in this would be really helpful.

Suggestion

• In ReadAloud's Options menu, allow selecting a voice + speed per language.
  Note:
  • Firefix' Settings / General menu (about:preferences#general), in Language / "Choose your preferred language for displaying pages" , click "Choose" - already provides the preferred languages to request pages in
  • these preferences are also seen in any Accept-Language HTTP request header
• Let ReadAloud choose the voice + speed to read the page in by matching the selected languages to the value of the "lang" attribute of the page's HTML element.
• If no html.lang attribute provided, use the voice and speed for the most preferred language.
• Extend the context menu "ReadAloud selected text" to allow the language selection among the configured (above) to read the text. Let there also be a "default" option to apply the above logic.