add syntax highlight for html on template literals about sublime-babel-vscode

[joshpeng]

@developersoul I looked into it. This would be a pretty big feature set to try and create. The main issue is that the backtick for template literals don't necessarily mean it is for a template literal. Furthermore, it is incredibly difficult for tmLanguage to classify the proper grammar for the contents of the template literal.

I think the only feasible solution is to do similar to how language-babel package on Atom does it with a user-defined custom template prefix typed into the code before the template literal. This avoids the need of the babel grammar from trying to guess what embedded grammar is.

For example, in order to syntax highlight this

const template = `<div></div>`

You would need to first define a template prefix like /* @html */ and then shove that right before the template literal.

const template = /* @html */`<div></div>`

For now, I'll leave this as a feature request. Thanks.

[juangl]

It'd be nice to support it in this way.