[Fix #9316] Make Style/EmptyLiteral not register offense when using a numbered block

[agargiulo]

Fixes #9316

Hash.new { _1[_2] = [] } is valid code but the cop was not parsing the
numblock correctly when parsing ruby27. Now it treats both the above and
Hash.new { |h, k| h[k] = [] }
as valid statements.

Update the parsing in Style/EmptyLiteral#hash_with_block to account for numblocks in addition to regular block

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[koic]

Thanks!