Before, `bundle outdated --parseable` (or `--porcelain`) caused output
to be completely silenced during definition resolution, so nothing was
printed at all until the table of outdated gems was printed.

With this change, `--parseable`/`--porcelain` now prints progress to
stderr during resolution. E.g.:

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

This provides a better user experience, especially when
`outdated --parseable` takes several seconds or more.

The report of outdated gems is still printed to stdout, and the exit
status codes are unchanged, so the fundamental contract with other tools
consuming the `outdated --parseable` result should not be affected.

https://github.com/rubygems/rubygems/commit/7d4bb43570