Support two-way data binding for the `hoveredIndex` property

[joao-m-santos]

Feature description

It should be possible to do something like v-model:hovered-index="myIndexRef" in any Lume chart.

Problem/motivation

Currently, the only way to link the hoveredIndex of a chart to an "external" ref is by listening in to all hovered-index/tooltip related events, e.g.

<lume-bar-chart
  ...
  :hovered-index="myIndexRef"
  @tooltip-opened="myIndexRef = $event.index"
  @tooltip-moved="myIndexRef = $event.index"
  @tooltip-closed="myIndexRef = -1"
>

Using Vue's two-way data binding would be a better, cleaner approach to achieve the same result.

Describe alternatives you've considered

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Additional context

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Validations

• [X] Follow our Code of Conduct
• [X] Read the Contributing Guidelines.
• [X] Check that there isn't already an issue that request the same feature to avoid creating a duplicate.