Feat: tooltip for INPUT[slider]

[Cube707]

This PR implements the on-hover tool-tip for the INPUT[slider] object, similar to how it was added to the INPUT[progressBar] in #473.

When hovering the input, a small tool-tip will be displayed under the center of the slider showing the current value.

---

I also modified the on-hover behavior of the progress bar to make the two components consistent.

Previously one had to hover over the "filled" part of the progressbar and the tool-tip would be centered on that part.

Now the label is on the container. That means both components can now be consistently be hovered anywhere and will get the tool-tip.

---

Testing

test it using:

---
exampleProperty: 13
---

```meta-bind
INPUT[slider(addLabels):exampleProperty]
```

```meta-bind
INPUT[progressBar:exampleProperty]
```

[Cube707]

closes #519

[mProjectsCode]

Thanks :)