Make Woo Activity / Inbox available site-wide

[manospsyx]

The Woo Admin Header bar is currently only available on "WooCommerce" pages / areas only, which is sub-optimal for a few reasons:

• it takes up a lot of space in comparison to the utility it provides
• it limits the visibility/access to the Inbox to specific areas only

The goal of this task is to make the Inbox available site-wide in the WP Admin bar:

To do this, we could:

• Register the Woo Header Bar in all WP Admin screens -- not just "Woo" screens.
• Add a new Activity icon in the WP Admin top bar -- and on click, trigger the Woo Header Bar "Activity" button.
• Tweak some CSS to "hide" the white Woo Header Bar:

.woocommerce-layout__header-wrapper {

    min-height: 0 !important;
    height: 0;

   & > h1, woocommerce-layout__activity-panel-tabs  {
        height: 0;
        overflow: hidden;
    }
}


#wpbody {
    margin-top: 0;
}

Ideally, this should not affect the function of other nudges/prompts that rely on the Woo Header Bar -- e.g. feedback tips/prompts -- and if it does, any issues could be ironed out with CSS.