Site health: Load the "Info" tab immediately and notify the user while gathering site data. Changes the Info tab to work similarly to the Status tab: it does separate request to fetch the directories sizes and doesn't "block" the loading of the page.

Props xkon, afercia, Clorith, azaozz.
See #46707.

git-svn-id: https://develop.svn.wordpress.org/trunk@45176 602fd350-edb4-49c9-b593-d223f7449a82

src/wp-admin/css/site-health.css

@@ -377,6 +377,13 @@
 	margin-left: 22px;
 }
 
+.health-check-wp-paths-sizes.spinner {
+	position: absolute;
+	visibility: visible;
+	float: none;
+	margin: 0 4px;
+}
+
 @media screen and (max-width: 782px) {
 	.health-check-body {
 		margin: 0 12px;