📎 Support for cross language lint rules (`noUnusedVariables`, `noUnusedImports`, etc)

[dyc3]

Description

Right now, users are unable to use these very valuable rules because they currently don't function across language boundaries:

• noUnusedVariables
• noUnusedImports
• useImportType
• useConst

All of these rules rely on the semantic model to feed them the correct info. However, its currently confined to just javascript, and is unable to inspect the contents of the parent HTML-ish language to continue building the semantic model.

[ematipico]

What kind of discussion are we looking for?

[dyc3]

I mostly just want to collect info on the task here. It's kinda spread out in different places and in our heads, atm.

I remember us talking about adding an additional(?) service to support this (can't find the convo now). But if you've already assigned yourself, it seems like you already have a pretty good idea of how this is going to work :)

[ematipico]

Yeah I already have a working branch with noUnusedVariables.

The code is quite raw, but I'm getting there. There are few things I need to change in the svelte parser

[ematipico]

@dyc3

What's a use case we need to fix for useImportType?