Add optional debug information for dumping instantiations (#6950)

Add optional debug information for dumping instantiations (#6950)

This complete the implementation of dump-instantiations-debug.

With this option, we can print the source of instantiations. For example:

$ cvc5 regress1/quantifiers/dump-inst-proof.smt2 --dump-instantiations-debug --produce-proofs
unsat
(instantiations (forall ((x Int)) (or (P x) (Q x)))
  (! ( 2 ) :source QUANTIFIERS_INST_E_MATCHING_SIMPLE ((not (= (P x) true))))
)
(instantiations (forall ((x Int)) (or (not (S x)) (not (Q x))))
  (! ( 2 ) :source QUANTIFIERS_INST_E_MATCHING_SIMPLE ((not (= (S x) false))))
)