Fix for sygusToBuiltinEval for non-ground composite terms (#5466)

Fix for sygusToBuiltinEval for non-ground composite terms (#5466)

There was a bug in the method for computing the evaluation of a sygus term applied to arguments.

The case that was wrong was for (DT_SYGUS_EVAL t c1 ... cn) where t contained a subterm (op t1 ... tn) where:
(1) (op t1 ... tn) is a non-ground sygus datatype term
(2) op was an operator of the form (lambda ((z T)) (g z xi)) where xi is a variable from the formal argument list of the function to synthesize.
In this case, xi was not getting replaced by ci.

This bug appears when using sygus repair for grammars with composite term that involve variables from the formal argument list of the synth-fun.