Matthew Pickering authored Apr 11, 2023 and Francesco Gazzetta committed May 28, 2023

It is necessary to modify `./Setup configure` to allow users to
configure a package *without* having previously built the dependency.
Instead, we promise to the configure phase that we will have built it
by the time we build the package. This allows us to configure all the
packages we intend to load into the repl without building any
dependenices which we will load in the same session, because the
promise is satisifed due to loading the package and it's dependency
into one multi-session which ensures the dependency is built before
it is needed.

A user of ./Setup configure specifies a promised dependency by
using the "--promised-dependency" flag with a normal dependency specification. For example:

```
   '--promised-dependency=cabal-install-solver=cabal-install-solver-3.9.0.0-inplace'
```