[WIP] LSP integration

[bjorkstromm]

@gep13 or @agc93 anyone of you want to continue with this? The newer OmniSharp builds now has much more stable LSP implementation.

[agc93]

Yeah, I'll try and have a look. I was chatting to @madskristensen about this stuff this morning so I want to try and give it another crack with the more stable bits from O# and the more stable bits from the VS end as well.

[agc93]

Currently blocked running into OmniSharp/csharp-language-server-protocol#132.

For my own reference, we still have a couple of big questions to sort out before we ship this:

• Do we ship O# in-VSIX? Download on first use?
• Do we try and locate/use the O# used from VS Code if its available?
• How do we stop the server? Does StopAsync actually get called or is it usual VS trickery?

[bjorkstromm]

@agc93 I’ve submitted a fix to OmniShatp here OmniSharp/omnisharp-roslyn#1503, once that’s merged, you can get the latest OmniSharp bits from the blob and try this out agan.