Use openerTabId to maintain tree position

[cjallen88]

I noticed while using this extension that when the new containerized tab is created and the old one removed, that the position in the tab tree (I'm using sideberry extension, but probably affects other tree style tab exts) gets confused.

See images below - when the new tab is opened by clicking 'management console' under an account, the parent somehow absorbs the next sibling tab as a child.

Before opening tab:

After opening tab:

This change appears to fix the issue

[cjallen88]

This didn't reliably fix it after all, I've made another local change to take better care around functions that return promises, so we'll see how that goes.