Summary:
Added the option to turn on noise behind the blurred area.
The lowest strength value disables it completely, so it is optional and is disabled by default.
Test Plan:
Edit: this new screenshot shows the updated noise generation.
Edit2: separated the screenshots so you can flick through them to clearly see the differences
{F5694024}
{F5694031}
{F5694025}
{F5694028}
Reviewers: #kwin, #vdg, fredrik
Reviewed By: #vdg, fredrik
Subscribers: davidedmundson, matheusm, romangg, ivan, zzag, ngraham, kwin, #kwin
Tags: #kwin
Differential Revision: https://phabricator.kde.org/D10281
cc0325af41