implement to_radix

[guipublic]

Description

Implement to_radix

Remove split and to_bytes directives/opcodes so that we only have one to_radix gate and directive.
I added a to_radix built-in which is used by to_bytes. We still need the to_bits builtin in order to benefit from boolean types.
I also refactored comparisons in acir_gen to use range_constraints.

Checklist

• I have tested the changes locally.
• I have formatted the changes with Prettier and/or cargo fmt with default settings.
• I have reviewed the changes on GitHub, line by line.
• I have ensured all changes are covered in the description.

[vezenovm]

Some minor nitpicks. I think you also need to merge in master as this branch references a bad version of aztec_backend that was redownloading the CRS on every nargo prove.