Adds detection logging messages at info level

[pivotal-david-osullivan]

Summary

This PR adds additional logging when Detect returns false for this buildpack. This is to provide more information about why the detection failed for this buildpack when verbose/debug logging is enabled.

As of lifecycle v1.16.0, if the detect phase fails as a whole, log messages are printed at info level by default, without the need for the verbose flag.

Use Cases

A pack build command with the --verbose flag set will show these log statement if detection fails. If Detect succeeds, the output is not shown unless --verbose is set.

Checklist

• I have viewed, signed, and submitted the Contributor License Agreement.
• I have linked issue(s) that this PR should close using keywords or the Github UI (See docs)
• I have added an integration test, if necessary.
• I have reviewed the styleguide for guidance on my code quality.
• I'm happy with the commit history on this PR (I have rebased/squashed as needed).

[dmikusa]

A few comments...

1. Same as on the other related PRs, what do you think about passing a logger to libpak.NewConfigurationResolver so that we see the env variable state when there's an issue? Seems like it could be helpful.
2. Line 88. Do you think it would make sense to add a log statement there? It's not a case that would cause the buildpack to skip, but it does cause a difference in behavior with the buildpack. Maybe it would be helpful to log something there.

[pivotal-david-osullivan]

1. Thanks - I added this, it's only useful if there are env-vars as part of the detection but we shouldn't have a config-resolver if there are none.
2. I added this too for extra info