New Block Widget: Add Visibility Options

[kspilarski]

What problem does this address?

In the new block widget, there is no option to configure visibility.

New block widget (without visibility options):

Classic widget (with visibility options):

(In an AT site, even widget-visibility is enabled, visibility is not available. Workaround is to install Classic Widget plugin.)

• User report: 30758048-hc

What is your proposed solution?

Add visibility option in the new block widget to display blocks in particular posts or pages of the site.

[mtias]

Widget visibility is a Jetpack feature, not a core one. I believe it's supported for non-block widgets already, but you can follow up on Automattic/jetpack#20057