Fix recent item deduping & call hooks

[colemanw]

Overview

Fixes a bug when adding to the "recent items" list, where the same item would sometimes be added twice.
Also adds a fix to call hooks when deleting items, for consistency with add.

To reproduce

1. Go to the contact menu and click on "new activity".
2. Save the new activity. Note that it is now in the recent items list.
3. Click on the activity in the recent items list.
4. Note that it is now in the list twice.

Technical details

Strict type checking using === was overkill, as CiviCRM uses string and int values interchangeably. E.g. activity id 123 was being compared to the string "123".

[civibot]

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[colemanw]

@lcdservices when you have a sec could you run through the steps to reproduce above & comment? This affects the recent items menu (as well as the existing recent items block).

[lcdservices]

Confirmed -- prior to the patch, a duplicate recent item was listed after creating and then viewing the activity. After the patch there is no duplicate.