Make the dependent biosphere database visible in the CF table

[mrvisscher]

Because the biosphere3 database isn't necessarily the only elementary flow database anymore, it is necessary to show what database the characterization factor in the CF table is from. This PR enables that functionality.

Checklist

• Keep pull requests small so they can be easily reviewed.
• Update the documentation, please follow the numpy style guide.
• Update tests.
• Categorize the PR by setting a good title and adding one of the labels:
  bug, feature, ui, change, documentation, breaking, ci
  as they show up in the changelog.
• Link this PR to related issues by using closing keywords.
• Add a milestone to the PR (and related issues, if any) for the intended release.
• Request a review from another developer.

[coveralls]

coverage: 54.132%. remained the same
when pulling 89f28fa on mrvisscher:visible-db-for-cf
into f28bdbd on LCA-ActivityBrowser:main.

[marc-vdm]

Maybe move the col to after Unit as this is not so important information but then LGTM