Several addons [GSoC]

[drmenzelit]

Hello @ranbuch ,
we took a weekend to rewrite the code in typescript and now here is the pull request like promised so your script benefits from the new features, too. We would like to ask you to review the code, thank you in advance.

The list of features are:

• We fixed the demo (moved everything to the "site" folder)
• List of improvements from GSoC student: Final evaluation feedback joomla-projects/gsoc22_accessibility-plugin-script#9
• Made a11y accessible with keyboard
• Users can change the speech velocity
• Implement increase / decrease line height
• Fixed the italic icons and corrected the emoji for underline links
• Made text-to-speech-language and speech-to-text language change to the currently active language of the site. Default is en-US. If the language is not supported then tts will not be displayed.

Looking forward to your feedback

[ranbuch]

Thank you @drmenzelit

I've made some small changes but it's merged to master. The main issue is we cannot debug the package without rebuild it when running it on http://localhost:8080/site/ with npm start.

Also, I'm not sure you've added your improvements to the readme file and the index.html.