Evaluate if we should add Sorbet

[vinistock]

Evaluated the advantages and disadvantages to add Sorbet to the ruby-lsp, so that we can decide on whether we want to do it or not.

If the decision is to add Sorbet, add it using our default tooling.

[egiurleo]

@vinistock How did we decide to add Sorbet? (To be clear, I'm all for it, just curious what factors went into the decision.)

[vinistock]

Our default is to use Sorbet in all projects unless there's a good reason not to. It provides better safety with a super short feedback loop, better editor support among other things.

Initially, I was pushing back on adding it because I had two concerns:

1. It felt a bit odd to me to have the sorbet-runtime as a dependency of this gem
2. I thought it'd be beneficial to have people experience the Ruby LSP on its own when working on it, without the Sorbet LSP, to find gaps in the experience more easily. Adding Sorbet means that some LSP functionality will start working, despite it not being implemented in the Ruby LSP (which we may want to do)

However, I believe the advantages are greater than these two. Because the Ruby LSP is used as a standalone executable, the addition of sorbet-runtime as a dependency is not really a problem. Also, using the Ruby LSP + the Sorbet LSP together is the experience we recommend, so it actually makes sense for us to test both together.

[egiurleo]

Awesome, thank you!

[Morriar]

Let's close this since we already decided to add it: #119.