Provide tooltip for Title and each Axis (Vaadin Charts 2)

[vaadin-bot]

Originally by basil.bourque

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In Vaadin Charts 2, the tooltip balloons on each DataSeriesItem (data points on chart line) work well.

Suggestion: Display a similar tooltip balloon on the Title and on each Axis.

Motivation: I show many charts on a layout, so I need make the most of my limited pixels. I disable the axis labels to save space. I still have the numbering scale on each axis. It would nice if, when the user hovered over that numbering scale of the axis, I could provide a tooltip with explanatory info such as "Total Net Generation, in Megawatts".

So too it would nice to have a tooltip for the title. To keep the interface clean and simple, I keep each chart’s title short and sweet. But for new workers, it would be nice to provide a fuller explanation of the chart while they are learning my app.

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Imported from https://dev.vaadin.com/ issue #16518