Report details about language server shutdown

[radeksimko]

Probably it is good for the server to reveal the reason of non 0 exit/unhandled error too.

Originally posted by @CallMeLaNN in #341 (comment)

I agree that the current messaging doesn't provide much details for debugging:

Launching language server: /Users/radeksimko/.vscode/extensions/hashicorp.terraform-2.0.0-rc.0/lsp/terraform-ls serve
[Error - 5:09:34 PM] Connection to server is erroring. Shutting down server.
[Error - 5:09:34 PM] Connection to server is erroring. Shutting down server.
[Error - 5:09:34 PM] Connection to server is erroring. Shutting down server.
[Error - 5:09:34 PM] Connection to server is erroring. Shutting down server.

I'm not sure how easy it is to expose more details, but from end-user perspective I'd really like to see:

• stderr
• exit code
• any related error

for the last and/or first run (assuming that the extension does attempt to restart the server).