Support displaying match games

[Drarig29]

Closes #76

Leverages this API: https://developer.mozilla.org/en-US/docs/Web/API/Popover_API

However, currently this is only supported on Chrome and Edge.

To support Firefox, you will need to add this manual polyfill for now:

<style>
    [popover] {
        display: none;
        position: absolute;
        background: white;
        border: 1px solid black;
        z-index: 1000;
        left: 50%;
        top: 50%;
        transform: translate(-50%, -50%);
    }

    /** Custom class to replace pseudo-class `:popover-open`. */
    [popover].popover-open {
        display: block;
    }
</style>

<script>
    function clearPreviousPopoverSelections() {
        document.querySelector('.popover-selected')?.classList.remove('popover-selected')
    }

    document.addEventListener('click', (event) => {
        clearPreviousPopoverSelections()
        document.querySelector('[popover]').classList.remove('popover-open')
    })
</script>

And your bracketsViewer.render() call should look like this:

await window.bracketsViewer.render({
  stages: data.stage,
  matches: data.match,
  matchGames: data.match_game,
  participants: data.participant,
}, {
  onMatchLabelClick: (match) => {
    if (match.child_count > 0) {
      clearPreviousPopoverSelections()
      document.querySelector('[popover]').classList.add('popover-open')
    }
  },
})