Added Open Impact Category to Calculation Setup screen

[mrvisscher]

Added ABAction to open method(s) and added the option to open methods directly from the calculation setup screen.

• Closes LCA setup: add 'open impact category' to context menu #1208

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: 54.344% (+0.02%) from 54.328%
when pulling 67c4a09 on mrvisscher:open-method-from-cs
into 54d6a9c on LCA-ActivityBrowser:main.