Allow customizing the name of the option for enabling tracing

[nhedger]

Feature request

AFAIK the only way to enable tracing for messages exchanged between the client and server is to set <langId>.trace.server to verbose. It would be nice if we could specify a custom configuration option from where to retrieve this value. For example, I'd like to use something like <langId>.lsp.tracing, because it better aligns with other config options of my extension.

I am willing to submit a PR that implements the feature if that is something you'd be open to.

[dbaeumer]

Makes sense. PR welcome.