Set resolveProvider capability to false

[neilyio]

It's my understanding that the resolveProvider: true property in the completionProvider capability in the Language Server Protocol (LSP) signals that the language server can resolve extra details for a completion item. A language server that specifies resolveProvider: true should typically implement a completionItem/resolve handler, which the client will call to resolve a completion item returned from the textDocument/completion request.

The client I'm using, helix, checks the completionProvider capbility, sees true, and calls completionItem/resolve. Since the emmet-ls connection doesn't implement onCompletionResolve, this causes a "method unhandled" error.

The comment in server.ts suggests that resolveProvider may have been set to true with the assumption that it simply enables completion. It should be false unless emmet-ls chooses to implement completionItem/resolve.