Due to a typo in the spec, the issue was not caught initially. If
Bundler does not need to re-resolve, `bundle lock` is a noop so Bundler
does not add checksums.

To fix the issue, we do something similar to what `bundle install` does,
just without actually installation. First set the domain (local or
remote) according to whether a re-resolve is necessary, and then
materialize lazy specifications into real specifications, so that
checksums are actually fetched from each source.

https://github.com/rubygems/rubygems/commit/84b6f4ee96

All we need is to setup remote or local sources appropriately.

https://github.com/rubygems/rubygems/commit/3ceff46a2a

https://github.com/rubygems/rubygems/commit/0a9c1ce60d

https://github.com/rubygems/rubygems/commit/1f93a2bdc5

`bundle lock --print --update` can take a long time to fetch sources and
resolve the lock file.

Before, `--print` caused output to be completely silenced, so nothing
was printed at all until the resolved lock file is finally emitted to
stdout.

With this change, `--print` now prints progress to stderr. E.g.:

```
Fetching gem metadata from https://rubygems.org/.........
Resolving dependencies...
```

This provides a better user experience, especially when
`lock --print --update` takes several seconds or more.

The lock file is still printed to stdout, so tools consuming the lock
file on stdout will not be affected.

https://github.com/rubygems/rubygems/commit/6719baa700

https://github.com/rubygems/rubygems/commit/6a0c03c77f

https://github.com/rubygems/rubygems/commit/2720da2659

https://github.com/rubygems/rubygems/commit/fd2e71dfdb