Introduce Admin Notifications to inform Admins about important changes

[imath]

During October 2 dev-chat, we've discussed about a way to warn Admins about the upcoming major change and advise the ones using BuddyPress plugins to install the BP Classic plugin.

As Admin notices are beginning to be treated as spams, I thought we should take this opportunity to build our our Admin Notifications center (waiting for the WP Notify feature as a plugin to be merged in WordPress).

We already have the Notifications component, but as it has to be available even if this component is inactive, I haven't used it. But I've used the WP Admin Bar bubble it normally generates when it is active.

When the notifications component is active, if the current user is an Admin and there is one or more Admin notifications, these will replace the regular notifications as long as they are not dismissed. Here's a screenshot about this Admin Notifications center.

As you can see into the Bubble we simply have an exclamation point with a bright red background, clicking on the link is bringing the Admin to the Notifications Admin screen where he can dismiss notifications or click on Action buttons (which also dismissed the corresponding notifications).

If we go this road, we'll need to backport these commits in 11.4.0:

• [13576]
• part of [13594]: line 1578 to 1591 of trunk/src/bp-core/classes/class-bp-admin.php

• Add a new Administration screen to list Admin notifications.
• Put the logic in place to dismiss an Admin notification.
• Add a 11.4 update task to add unread Admin notifications.

@dcavins If you think we can use this to reply to our need to make sure to alert Admins about the fact they may install BP Classic, I'd love you to review the Admin Notifications texts.

Trac ticket: ​https://buddypress.trac.wordpress.org/ticket/9007

This looks terrific! Thanks for setting up a way to display this message to admins. Now we just have to hope that our friendly admins read the message and take the necessary steps. :)

Here's the current state of the notification:

What do you think of this language? It's long, so I tried to add some structure to it.

@dcavins It's perfect! Thanks a lot for your work on this 💪

[imath]

In 13612:

Use the author field to query Add-ons via the WP.org Plugin API

Backports [13576] to branch 11.0.

See #8984
See #9007

[imath]

In 13613:

Show BP Classic plugin details when requested, on page load

Backports part of [13594] to branch 11.0.

See #9002
See #9007

[imath]

In 13614:

Introduce Admin Notifications to warn Admin about important BP changes

• Add a new Administration screen to list Admin notifications.
• Put the logic in place to dismiss an Admin notification.
• Add a 11.4 update task to add unread Admin notifications.
• Create a 11.4 Admin Notification to inform Admin users about whether they need to install BP Classic to be ready for BuddyPress 12.0.0

Props dcavins

Closes ​https://github.com/buddypress/buddypress/pull/176
See #9007 (trunk)

[imath]

In 13615:

Introduce Admin Notifications to warn Admin about important BP changes

• Add a new Administration screen to list Admin notifications.
• Put the logic in place to dismiss an Admin notification.
• Add a 11.4 update task to add unread Admin notifications.
• Create a 11.4 Admin Notification to inform Admin users about whether they need to install BP Classic to be ready for BuddyPress 12.0.0
• Bump Raw DB version to 13408

Props dcavins

Fixes #9007 (Branch 11.0)