Groups consecutive function clauses with the same name/arity into synthetic compound nodes so the fingerprinter can detect duplicated multi-clause functions.

Also groups delegation wrappers with their target clause. A delegation is when a lower-arity clause simply calls the same function with extra default arguments:

def fetch(id), do: fetch(id, [])
def fetch(id, opts) do ... end

These are grouped into a single __ex_dna_grouped_def__ block so the fingerprinter can detect duplicated wrapper+body patterns across modules.