history-dialog: Add selection mode

Closes GNOME/epiphany#903
3 jobs for HistorySelectionMode in 17 minutes and 42 seconds (queued for 1 second)
Status Job ID Name Coverage
  .Pre
passed #809494
check-code-style

00:00:54

 
  Test
passed #809495
flatpak
flatpak

00:16:48

passed #809496
flatpak
flatpak scanbuild

00:13:20