Add support for an HTML language server

Hello, I am almost certain that this is already a feature. However I could not find an answer yet to this. As I am short on time, I figured that opening an issue could be the best option.

Is there a way to have the same completion capabilities that ALE gives in TS and JS on HTML? In this matter, whenever I type properties like `class`, `src` or even tags... ALE does not gives any suggestions. It is not a big deal but it would certainly shorten my work if I could do it without `ins-completion`.

Thanks in advance!