fn_to_numeric_cast_any: Do not warn cast to raw pointer

[taiki-e]

Fixes #12638

changelog: [fn_to_numeric_cast_any]: Fix false positive on a cast to raw pointer

[rustbot]

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[Jarcho]

I wonder if this should just be renamed instead. How often would you want to find just the non-truncating casts, but not also want the pointer ones?

[taiki-e]

I know of several code bases with use cases where to_ptr is valid and to_numeric is not. All such use cases I know, convert function pointers to raw pointers for using with AtomicPtr. e.g., memchr