Avoid creating functions at jump table entries in shared cache

[plafosse]

Summary

• When processing shared cache Mach-O function tables, Binary Ninja was creating functions at addresses that turn out to be jump table entries rather than real function starts, producing spurious sub_ functions.
• Adds a HeuristicIsAFunction check before calling AddFunctionForAnalysis. On aarch64, if the first instruction at the candidate address disassembles as udf, the entry is skipped — udf is used as padding/data in jump tables and is never a valid function prologue.
• This heuristic is admittedly a bit rough and could produce false negatives in unusual cases, but it directly addresses the reported symptom.

Fix #7992