By default, we will build source distributions for both resolving and
installing, running arbitrary code. `--no-build` adds an option to ban
this and only install from wheels, no source distributions or git builds
allowed. We also don't fetch these and instead report immediately.
I've heard from users for whom this is a requirement, i'm implementing
it now because it's helpful for testing.
I'm thinking about adding a shared `PuffinSharedArgs` struct so we don't
have to repeat each option everywhere.
This PR makes the cache non-optional in most of Puffin, which simplifies
the code, allows us to reuse the cache within a single command (even
with `--no-cache`), and also allows us to use the cache for disk storage
across an invocation.
I left the cache as optional for the `Virtualenv` and `InterpreterInfo`
abstractions, since those are generic enough that it seems nice to have
a non-cached version, but it's kind of arbitrary.
Show the resolution in a concise format for puffin-dev. Note that this
doesn't affect the main puffin output, it's just more convenient for me
when developing.