Use a custom PubGrub error type to always show resolution report (#365)
Closes https://github.com/astral-sh/puffin/issues/356.
The example from the issue now renders as:
```
❯ cargo run --bin puffin-dev -q -- resolve-cli tensorflow-cpu-aws
puffin-dev failed
Caused by: No solution found when resolving build dependencies for source distribution:
Caused by: Because there is no available version for tensorflow-cpu-aws and root depends on tensorflow-cpu-aws, version solving failed.
```