Default to the annotations tab when user switches between groups, clears a selection or reloads a page.
The ANNOTATIONS_SYNCED event is emitted when annotations for a document have finished anchoring. Because annotations are not marked as orphans until they fail to anchor, select the annotations tab after they have finished anchoring.

Test cases:
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1. On page load localhost:3000
   annotations tab is selected.
   clicking on new note switches to the notes tab with a new draft created.
   switching between tabs maintains tab selection, if notes or annotations.
   when tab selected is orphans, changing groups defaults to the annotations tab.
2. On page load localhost:3000/#annotations:<id>
   clicking on new page note should select the notes tab.
   When an annotation/note is selected, the tab selection carries between group changes.
   all tests listed in #1 above should apply.
3. On page load  localhost:3000/#annotations:<orphan_id>
   clicking on “show all annotations and notes” selects the annotations tab and displays all annotations.
   all tests listed in #1 and #2 above should apply.
   switching between groups selects the annotations tab by default

https://trello.com/c/1NVK2jwv/400-add-a-tab-for-unanchored-annotations
https://trello.com/c/OLdLTlLT/342-separate-annotations-and-notes

Hide orphans tab behind orphans_tab flag.

Fix bug where notes tab isn't selected when user attempts to create a new page note.