Better filtering for plugin updates

Posting this here as per Bojan’s suggestion in support ticket #28473307

We’ve found ourselves needing to filter child sites, and updates in a way that isn’t currently possible without a workaround that requires hundreds or thousands of mouse clicks.

Basically we want to be on this page:

/wp-admin/admin.php?page=UpdatesManage&tab=plugins-updates

but we need the filtering sidebar that’s seen on the right side of:

/wp-admin/admin.php?page=PluginsManage

I’ve attached a Photoshop mockup of what this would look like: