VS Code for development

[hopskipnfall]

It would be great to add VS Code as an alternative to IDEA for development, but finding a combination of settings and plugins that allow for a similar (even acceptable) development experience has proven difficult.

Requirements:

1. If I run ./gradlew compileKotlin to pull in all dependencies and compile the code and then open up the IDE, it should be able to index the entire repository (possibly requiring some human intervention to install plugins).
2. High quality autocomplete that isn't a fuzzy text search.
3. Recognizes compile-time errors when I write code that doesn't compile (without the developer having to run CLI commands).

Bonus points if it can infer types and bind to a debugger.

@CEnnis91 was working on a more ambitious attempt at this in #95 but it still needs work.

[hopskipnfall]

I should also note that the things that make this repository tricky for LSP are:

• We have a Kotlin file that is generated by a "filtering" step (CompiledFlags.kt)
• We have a compilation step where Dagger-generated Java files are created, so both Java and Kotlin files need to be indexed