Allow strings for EuiToolTip children

[smith]

The type for the children prop of EuiTooltip is React.ReactElement<any>. It expects this because it does a React.cloneElement to create the anchor.

Because it is of this type and not React.ReactNode, you cannot pass a string as children to a tooltip, so:

<EuiToolTip>{someValue}</EuiToolTip>

has to become:

<EuiToolTip><>{someValue}</></EuiTooltip>

It would be nice if we were more flexible and allowed any React.ReactNode as children.

[thompsongl]

I agree that React.ReactElement<any> is likely too strict. We do, however, need to consider a11y, so tab focus and keyboard navigation/interaction are a consideration and bare text is likely not an option. EUI could make assumptions about what to do with a string (e.g., wrap it in an EuiLink), but it'd have to be discussed.

[smith]

I don't think we need to sacrifice the developer experience for accessibility; we can have both. I started to just open a PR to fix it but realized there were design considerations that were needed. Thanks for looking!

[cchaos]

@smith Do you still hav that PR handy, we can certainly help with the design considerations.

[smith]

@cchaos No I checked on the branch and there's nothing there, so I don't think I made any changes back then. Thanks for looking!

[cchaos]

Related #4040 & #2027

[cchaos]

Closing in favor of a Meta discussion around EuiTooltip flexibility which I've included a link to this discussion but needs to be a part of a greater effort.