[clang] [clang][ObjC][CodeComplete] Fix crash on C-Style cast with parenthesized operand in ObjC++ (PR #180343)

[Corentin Jabot via cfe-commits]

cor3ntin wrote:

@ojhunt but the expression here seems valid? it just does not have a type yet. So the fix seems reasonable?

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https://github.com/llvm/llvm-project/pull/180343