Capabilities override

[alcarney]

Provide a cli option to override the set of capabilities a set of tests are run with.

[alcarney]

Don't think we need to add anything special to support this, but adding some notes to the docs would be a good idea

[DetachHead]

it would be nice if lsp-devtools client also had an option to specify its capabilities. currently it just sends {}

[alcarney]

it would be nice if lsp-devtools client also had an option to specify its capabilities.

I agree, the client is just a proof of concept at this stage but I definitely want to get around to doing it "properly" at some point