add .astro files support

[KostiantynO]

Dear @klette, please add support for .astro files.

[markomitranic]

It is bad guy move from me, to post a link to another extension, but since this thread (and more like it) are over 2y old, here goes...

I've found that a significantly less popular https://marketplace.visualstudio.com/items?itemName=CraigRBroughton.htmx-attributes extension is out-of-the box able to do this on most files, such as astro, tsx or php.

I do not know how the functionality compares to this extension, but something is better than nothing...
I do wonder, is there an architectural difference between the two extensions, that prevents this one from implementing such a feature?