Fix false positives for Style/RedundantDoubleSplatHashBraces

[koic]

Fixes #12263.

This PR fixes false positives for Style/RedundantDoubleSplatHashBraces when method call for no hash braced double splat receiver.

The code shown in #12263 is incompatible as shown below and is a false positive:

def x(opts) = puts(opts)

h = {foo: :bar}

x(**h.merge(k: :h)) #=> {:foo=>:bar, :k=>:h}
x(k: :v, **h)       #=> {:k=>:v, :foo=>:bar}

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• Added tests.
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[bbatsov]

Thanks!