entry: use padding on the image area to position the image
entry: use padding on the image area to position the image

Don't assume the padding of the icons is the same padding of the rest of
the entry.
This also allows to set different paddings for left and right icons.

Lyude/gtk-,chergert/gtk,chergert/gtk,jessevdk/gtk,davidgumberg/gtk,Distrotech/gtk2,Distrotech/gtk2,jessevdk/gtk,ahodesuka/gtk,Adamovskiy/gtk,Lyude/gtk-,Adamovskiy/gtk,bratsche/gtk-,jigpu/gtk,davidgumberg/gtk,ebassi/gtk,alexlarsson/gtk,jadahl/gtk,grubersjoe/adwaita,grubersjoe/adwaita,ebassi/gtk,Adamovskiy/gtk,alexlarsson/gtk,jessevdk/gtk,Adamovskiy/gtk,jigpu/gtk,davidt/gtk,Lyude/gtk-,ahodesuka/gtk,jigpu/gtk,Adamovskiy/gtk,ebassi/gtk,davidt/gtk,jadahl/gtk,alexlarsson/gtk,msteinert/gtk,davidgumberg/gtk,jadahl/gtk,alexlarsson/gtk,Lyude/gtk-,ahodesuka/gtk,jadahl/gtk,Lyude/gtk-,bratsche/gtk-,Adamovskiy/gtk,davidgumberg/gtk,chergert/gtk,alexlarsson/gtk,jessevdk/gtk,bratsche/gtk-,Distrotech/gtk2,ahodesuka/gtk,ahodesuka/gtk,Sidnioulz/SandboxGtk,jadahl/gtk,Lyude/gtk-,jigpu/gtk,Distrotech/gtk2,alexlarsson/gtk,Distrotech/gtk2,jessevdk/gtk,grubersjoe/adwaita,bratsche/gtk-,chergert/gtk,msteinert/gtk,chergert/gtk,msteinert/gtk,jadahl/gtk,alexlarsson/gtk,ebassi/gtk,davidt/gtk,Adamovskiy/gtk,jessevdk/gtk,msteinert/gtk,davidgumberg/gtk,Sidnioulz/SandboxGtk,Sidnioulz/SandboxGtk,chergert/gtk,jigpu/gtk,jessevdk/gtk,grubersjoe/adwaita,davidt/gtk,Sidnioulz/SandboxGtk,ebassi/gtk,alexlarsson/gtk,davidgumberg/gtk,chergert/gtk,jadahl/gtk,msteinert/gtk,davidgumberg/gtk,ahodesuka/gtk,Sidnioulz/SandboxGtk,davidt/gtk,bratsche/gtk-,jadahl/gtk,grubersjoe/adwaita,jigpu/gtk,Sidnioulz/SandboxGtk,ahodesuka/gtk,Lyude/gtk-,davidt/gtk,jigpu/gtk,Lyude/gtk-,msteinert/gtk,ahodesuka/gtk,bratsche/gtk-,jigpu/gtk,davidgumberg/gtk,grubersjoe/adwaita,ebassi/gtk,grubersjoe/adwaita,Distrotech/gtk2,grubersjoe/adwaita,chergert/gtk,Adamovskiy/gtk