Replace modal's focusOnMount with a optional string providing more options.

[abotteram]

Is your feature request related to a problem? Please describe.
The Modal component (#6261) has a prop that can be passed to it (focusOnMount) just like the Popover. In the popover this can optionally be a string providing more option where to focus when the component mounts.

As discussed with @aduth this feature should be included in a future iteration.

Describe the solution you'd like
Allow the focusOnMount prop (https://github.com/WordPress/gutenberg/tree/master/packages/components/src/modal#focusonmount) to be either a boolean or a string, following the same pettern and options as the Popover.

Describe alternatives you've considered
A clear and concise description of any alternative solutions or features you've considered.

[draganescu]

Howdy @xyfi I wonder how much of this does #19997 solve? If not completely could we push that to cover this issue completely?

[aduth]

@draganescu If I recall, the primary goal here was to align Popover and Modal in how this prop works. On a brief glance of #19997, it seems to move in that direction.

[paaljoachim]

This PR might be associated.
#28574

[jordesign]

Just checking in on this request to see if it is still relevant - or if other changes to the modal have resolved it?

[jordesign]

With no further comments in the last month I'm going to close this issue. We can always re-open if needed.