[clang] [clang-format] NEVER allow && to be an unary operator. (PR #78852)

[S. B. Tam via cfe-commits]

cpplearner wrote:

Unary `&&` is a GCC extension to get the address of a label. See https://gcc.gnu.org/onlinedocs/gcc/Labels-as-Values.html

Does this PR change the formatting of reasonable code that uses unary `&&`, e.g. `void *ptr; /* … */ ptr = &&foo;` in a function body?

https://github.com/llvm/llvm-project/pull/78852