feat(watcher): add symbol queries for ruby rspec tests

[wassimk]

I've been using these symbols queries via ruby-lsp^1 on a Ruby on Rails RSpec application for the past few weeks with success. The watcher feature is so useful!

Most RSpec classes look like this:

RSpec.describe MyClass do
  it "my first test" do
    # ...
  end
end

It also covers name spaced modules like so, MyClass is the returned symbol.

RSpec.describe NameSpaceModule1::NameSpace2::MyClass do
  it "my first test" do
    # ...
  end
end

References:

[rcarriga]

Thanks for the PR! :smile: