Update compilation tests

[huitseeker]

• Expanded error messaging and debugging suggestions in several unit test files including 'normalize_complex.stderr', 'consume_head.stderr', and 'consume.stderr' related to trait bound not being satisfied and the Sub<Rhs> trait not being implemented for certain types.
• Enhanced error messages in 'sponge_creation.stderr' and 'sponge_bad_api.stderr' unit tests, addressing the mismatched expected types and clarification about specific Sub<B1> trait implementation.
• Comments have been added to the unit tests module in the Sponge API located in 'lib.rs' for improved clarity.
• Additional test assertions in 'normalize.stderr' unit test validate the trait implementation with Absorb<U4> type.