Actions missing from Sites Edit pages in new Network Admin

[mwidmann]

In 3.0.1 ms-sites.php called a couple of actions and filters which are now missing.

Especially the wpmueditblogaction hook is missing which allowed to add additional fields to the edit site form and then hook into wpmu_update_blog_options to store the additional settings.

While wpmu_update_blog_options is still there, it's available only in sites-info.php and missing in sites-options.php where imho it belongs.

A filter to add additional tabs to the site-edit functionality would be a nice addition as well.

Because wpmueditblogaction is missing the blog upload space setting can't be set, see upload_space_setting().
I will upload a patch to re-add the wpmu_update_blog_options action for back-compatibility.

Add filters to site-edit tabs.

Restore wpmueditblogaction hook in site-options.

(In [16627]) Add missign hooks in site-options. Fixes #15593

Ticket for tabs filter: #15800.