Make sending initial workspace config less fragile

[kitsonk]

Currently, when we add a config setting that the server needs to know about, we send the settings in the initial initialisation it uses the top level keys of the settings of the deno namespace to copy values into the response:

https://github.com/denoland/vscode_deno/blob/e5db81f2799af1896e04750b23cb8cf190b39ea6/client/src/extension.ts#L24-L39

This is fragile because if they are missed, there is no error, the server config simply is not accurate if an option has changed from its default.

See: #632