Proposed change: This would require the following changes:

1. Assess the memory consumption due to using String in many places such as Metadata crate.
2. Move the InternedString code out of the CBMC crate. Maybe create a kani_common crate.
3. Modify the crates that still heavily rely on String, such as the Metadata crate.

Motivation: Keeping strings can increase the memory consumption of our software.