Support Symbol#to_proc block inference

[pvcresin]

Summary

Fixes #414

Support Symbol#to_proc blocks such as map(&:to_i).

This treats a symbol passed as a block as a method call where the first yielded block argument is the receiver and the remaining yielded arguments are method arguments.

Changes

• Infer ["1", "2"].map(&:to_i) as Array[Integer]
• Support the same Symbol#to_proc behavior for Ruby yield
• Add scenario coverage for RBS block calls and Ruby method block calls

[sinsoku]

I tried this branch against Redmine 6.1.1 with this script, and the analysis hangs (master finishes in under 20s). Could you take a look?

[sinsoku]

yield with keyword arguments is valid Ruby, e.g.:

def foo
  yield 1, key: "v"
end
foo { |x, key:| puts "x=#{x}, key=#{key}" } # => x=1, key=v

So I think @a_args.keywords should also be passed through to add_symbol_proc_call_box here.