Checklist: Add 'pending' State to steps

[ockham]

To reflect e.g. ongoing VaultPress or Akismet installation/setup/provisioning.

Draw inspiration from https://github.com/Automattic/wp-calypso/blob/master/client/my-sites/checkout/checkout-thank-you/jetpack-thank-you-card.jsx.

Fortunately, we only need a less fine-grained approach (i.e. we don't need feature granularity -- plugin granularity should be enough, e.g. VaultPress corresponds to the 'Backups and Scanning' step, Akismet to 'Spam Protection'). Should be enough to select plugins = getPluginsForSite( state, siteId, false ) in connect(), and do something like

wp-calypso/client/my-sites/checkout/checkout-thank-you/jetpack-thank-you-card.jsx

Lines 484 to 497 in 5e62832

	const pluginsStatus = reduce(
	plugins,
	( completed, plugin ) => {
	if ( 'done' === plugin.status ) {
	completed[ plugin.slug ] = 'done';
	} else if ( plugin.hasOwnProperty( 'error' ) && plugin.error ) {
	completed[ plugin.slug ] = 'error';
	} else {
	completed[ plugin.slug ] = 'wait';
	}
	return completed;
	},
	{}
	);

[tyxla]

This can now be closed - we're doing it in a different way than what's suggested here though. Installation, activation and configuration now happens on the server side, and the following PRs were responsible for making the "pending" state be displayed on the client.

#31684
#31547
#32152
#31963