Instead of drawing this all ourselves, drop it all in a `GtkGrid`. This handles all the padding and alignment for us, which is way more consistent, too.
Note, old code has not been removed because it's used in conversations.
Testing Done:
Hover over buddy list, try with keyboard `Ctrl+F1`.
Reviewed at https://reviews.imfreedom.org/r/754/
PidginandFinch:ThePimpin' Penguin IM Clients That'reGoodfortheSoul
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