Display tooltips on zero value bars

This is a follow-up to #3797 .

I am using ggplotly in R, not using plotly directly, so I'm not including a reproducible example, but I think the issue is straightforward.

The tooltip (using the "text" specified in the ggplot command) does not appear in barplots when the bar height is equal to 0. The issue cited above notes the same thing in the last comment, posted after that issue had been resolved/closed.

If the tooltip only included the value of the bar height, this would not be a problem. But we often use the tooltip to display multiple values. In my specific case, the bar height shows year-to-year percentage change for each state, and the tooltip includes both the pct chg and the raw number for the current year. The raw number provides useful interpretive context because there is a wide range of raw values, and small values lead to more variable/extreme pct changes. For the states with pct chg=0, no tooltip is shown, so we lose the information on raw number that would help provide context. Screenshot below for example.

Thanks!

首先在 plotly.js 中复现一个包含零高度柱条和自定义 tooltip 文本的柱状图，然后阅读相关 issue #3797 并比较其行为。当零值柱条显示其配置的 tooltip 内容（包括超出柱条高度的值）时，工作即告完成。