[balooctl] Use new helper in json output

Summary:
The output is mostly the same, save for the following fixes:

• symlinks are no longer listed as "indexing=basic, state=scheduled", but are omitted from output
• in case "onlyBasicIndexing" is active, indexing now shows "basic" instead of "content"
• excluded files are now "indexing=none, state=disabled" instead of "indexing=basic, state=disabled"

Depends on D20617

Test Plan: balooctl status -f json <file>

Reviewers: Baloo, Frameworks, ngraham, astippich, poboiko

Reviewed By: Baloo, ngraham

Subscribers: kde-frameworks-devel

Tags: Frameworks, Baloo

Differential Revision: https://phabricator.kde.org/D20619