Fix emerge output

Summary:
Change semantics slightly.

Now we have debug level:

-1 -> 'emerge -q'
 0 -> 'emerge '
 1 -> 'emerge -v'
 2 -> 'emerge -vv'
 3 -> 'emerge -vvv'

Changes;

• Now outputting generally useful info at debug level 0 already
  • Currently handled package
  • Current action (fetch, compile, qmerge, etc.)
  • Package result (success, failed)

Differential Revision: https://phabricator.kde.org/D724