Draft: applets/notes: Slide in/out format bar

There is a lot of room for improvement here but I don't know how to do any of it.

What's changed:

• The format bar now slides away when plasmoid focus is lost, instead of having it turn invisible but occupying space.
• There's now a separator above the format bar.
• Use textMargin and padding alternately in the TextArea depending on visibility of format bar.
• Change assumption of default SVG margins from 7% to 5%.

Issues:

• The Notes SVG is scaled in a way that the margins are constantly changing, so the horizontalMargins and verticalMargins are always wrong. Assuming it to be any percentage of the svg's width and/or height is wrong. But I don't know what to do about it.
• When focus is lost, the format bar slides away as expected but the text that would be below it is lost. Fixed in 12f38cf5
• Setting textMargin has caused the scrollview to default to a position slightly off from the starting position when you have a lot of text in the sticky note. Fixed in 12f38cf5