Add astro to supported extensions for Javascript

[Suven]

Hey!

Thanks for Poedit (: I am using the proversion and am currently in the process of writing a skeleton / tutorial for how to setup a SEO friendly multilingual project with Astro and po-files.

Astro is a very quickly growing and already big framework for creating SSG'd websites. It's pages have an extension of .astro but contain mainly js / tsx.

My tutorial will feature how to do the basic setup with gettext and show how Poedit can be used for the actual translation. It's nearly done and I will link it within this PR soonish.

It would be cool if I could explain how to use poedit, without needing to require profeatures to beginners. I think the only missing part for that is the extension-support.

Edit: Here is the project I was talking about https://suven.github.io/astro-po-i18n/

[vslavik]

This PR only changes the fileviewer, not anything about actual extraction, i.e. is clearly not tested.

This does not seem to be standard localization for Astro, so I don't think this is appropriate to merge, sorry. You have the option to customize file extensions in Poedit yourself for edge cases like this.