Add a GOTO binary serializer to cprover_bindings

[remi-delmas-3000]

Proposed change:

• Write a new serializer for IrepId, InternedString, Irep, Symbol and SymbolTable that directly targets the GOTO binary format.
• Implement full structural hashing and sharing of irep nodes and strings during serialization
• Update kani-driver to invoke goto-cc instead of symtab2gb to perform GOTO-conversion of the symbol table.

Motivation:
The current cprover_bindings SymbolTable serializer is based on the serde crate and serialises to JSON, which is then consumed by symtab2gb. The JSON encoding does not allow to reference strings or irep nodes hence causing a blowup in size on save, and symtab2gb is also costly (time and memory) to run.

By serializing the symbol table directly to GOTO binary we can skip the call to symtab2gb and save time and memory.