Add sort_by options for `get_functions`

[ttimasdf]

add sort_by parameter with some fixed options

• linear: Sort functions in linear order as they appear in the binary (default)
• most_bytes: Sort functions by size in bytes (largest functions first)
• most_callers: Sort functions by number of unique calling functions (most callers first)
• most_callees: Sort functions by number of unique called functions (most callees first)
• most_connected: Sort functions by total call graph connections (callers + callees)
• most_caller_sites: Sort functions by total call sites (counting duplicate calls from same caller)
• most_callee_addresses: Sort functions by total call instructions (counting duplicate calls to same callee)

Reference: Cookbook - Binary Ninja User Documentation