Use QtQuick.Controls 2.0 Label in energy and fileindexmonitor KCM

Summary:
The QtQuick.Controls 1.0 does not handle Label well on screens that uses a fractional scaling. The fonts become
blurry, this has been fixed in QtQuick.Controls 2.0 and org.kde.plasma.components, however we prefer to use QtQuick.Controls 2.0 since the modules will anyway transition to 2.x at some time.

CCBUG: 366451

Test Plan: * Use scaling 1,5 and fonts will appear correctly in kcm_energyinfo and kcm_fileindexmonitor

Reviewers: davidedmundson

Reviewed By: davidedmundson

Subscribers: zzag, davidedmundson, ngraham, broulik, plasma-devel

Tags: Plasma

Differential Revision: https://phabricator.kde.org/D14011