Allow braced numeric block calls in Style/MethodCallWithArgsParentheses

[gsamokovarov]

This is yet another fix for the omit_parentheses style of the
Style/MethodCallWithArgsParentheses cop. We're issuing offenses for
braced numblock calls:

updated_ids = Set.new(items_to_update) { _1.remote_id.to_s }
                     ^^^^^^^^^^^^^^^^^ Omit parentheses for method calls with arguments.

Removing the parens leads to code that doesn't compile so this is not good.

Numeric block have their own AST node type:

-> ruby-parse -e "Set.new(items_to_update) { _1.remote_id }"
(numblock
  (send
    (const nil :Set) :new
    (send nil :items_to_update)) 1
  (send
    (lvar :_1) :remote_id))

vs

-> ruby-parse -e "Set.new(items_to_update) { |it| it.remote_id }"
(block
  (send
    (const nil :Set) :new
    (send nil :items_to_update))
  (args
    (procarg0
      (arg :it)))
  (send
    (lvar :it) :remote_id))

Send nodes can be queried for their block if given with #block_node,
however, the numblocks don't get recognized as such. Our check for braced
block calls used to rely on it:

https://github.com/rubocop/rubocop-ast/blob/master/lib/rubocop/ast/node/mixin/method_dispatch_node.rb#L35-L37
https://github.com/rubocop/rubocop-ast/blob/master/lib/rubocop/ast/node/mixin/method_dispatch_node.rb#L156-L158

I'm changing the implementation to work around this issue and recognize
numblock braced calls, but we may consider moving the fix to
rubocop-ast as well.

[koic]

Thank you, Genadi!