…t packages

Now, it is possible to build any package of the workspace in a fine grained fashion.

We want here to capture the required data to assemble a stub, here is a partial structure
modulo ESP generation paths.

Other pieces of code can consume this structure, validate it before passing it to the PE assembler
and the signer.

We convert everything into owned structures because we cannot really do
deserialization in any context with lifetimes going around, but,
allocations are generally very cheap in this context.

In order to offer more flexible signature mechanisms in lanzaboote,
we need to take a step back and offer a general PE signature trait.

After this, we will be able to plug various different implementations.

Our lanzaboote integration tests are getting more and more sophisticated and ambitious.

Let's extract them into a "lanzalib", so they can be used with multiple backends.

We didn't test if there *was* a signature, idempotency of removal of signatures (i.e. removing an non-existent signature
is the identity operation) could fool us into believing we had a signed thing then not signed.

We fabricated a lot of initrds which were exactly the same as the one in
our store when we had no initrd secrets. This ends this practice.