Add autocomplete for asconfig.json

Add autocomplete via json scheme 

### Implementation Plan

+ Create JSON scheme for `asconfig.son` based on [this file](https://github.com/AssemblyScript/assemblyscript/blob/main/cli/options.json), but preserve structure.
+ Add JSON scheme to [schemastore](https://www.schemastore.org/json/) in their [repository](https://github.com/schemastore/schemastore/)