Symbol/WordArray style "percent" should also consider [ ] chars as "bad"

[johnnyshields]

The current behavior of the Symbol/WordArray cop's default style ("percent") is as follows:

# bad
[:foo, :[]=]

# bad (contains spaces)
%w[foo\ bar baz\ quux]

# good (allows [ ] chars)
%i[foo \[\]=]

I think we should change this so that [ ] trigger the same special handling that space char does, and the preferred style here would be [:foo, :[]=]

[bbatsov]

Makes sense to me. PR welcome!

[johnnyshields]

@koic Awesome, thank you!