The 3rd kind of assignment kind (Bind) is gone and now reflected through a boolean parameter. Note that this parameter is completely erased by the type-checker so that the rest of the pipeline (i.e. code-generation) doesn't have to make any assumption. They simply can't see a backpassing let or expect.
This is more holistic and less awkward than having monadic bind working only with some pre-defined type. Backpassing work with _any_ function, and can be implemented relatively easily by rewriting the AST on-the-fly.
Also, it is far easier to explain than trying to explain what a monadic bind is, how its behavior differs from type to type and why it isn't generally available for any monadic type.
We'll piggyback on the tracing capabilities of the VM to provide labelling for prop tests. To ensure we do not interfere with normal traces, we only count traces that starts with a NUL byte as label. That convention is assumed to be known of the companion fuzz library that should then provide the labelling capabilities as a dedicated function.
Before this commit, we would always show the 'declared form' of type aliases, with their generic, non-instantiated parameters. This now tries to unify the annotation with the underlying inferred type to provide even better alias pretty printing.
Somehow, these have always been right-associative, when the natural thing to expect is left-associativity. It now matters when trying to crawl down binary tree to display them properly.
Using ByteArrays as vectors on-chain is a lot more efficient than relying on actul Data's list of values. From the Rust end, it doesn't change much as we were already manipulating vectors anyway.
Also, this commit makes `apply_term` automatically re-intern the
program since it isn't safe to apply any term onto a UPLC program. In
particular, terms that introduce new let-bindings (via lambdas) will
mess with the already generated DeBruijn indices.
The problem doesn't occur for pure constant terms like Data. So we
still have a safe and fast version 'apply_data' when needed.
