Added "Transparent with light text" theme for Desktop Notes

Summary:
This commit adds one more simple theme for Desktop Notes, for ones who prefer the dark background and want to put sticky notes on it.

BUG: 386833

Before:
{F6455193}

After:
{F6455194}

Reviewers: #plasma, davidedmundson

Reviewed By: #plasma, davidedmundson

Subscribers: shubham, abetts, ngraham, plasma-devel

Tags: #plasma

Differential Revision: https://phabricator.kde.org/D17360