Baggins skin errors: GetContainerItemInfo is nil + unpack(nil)

Baggins skin uses outdated API for retail.  `AS.BorderColor` may be nil in SetBankVisual

```
AddOnSkins/SkinsBaggins.lua:85: attempt to call global 'GetContainerItemInfo' (a nil value)
AddOnSkins/SkinsBaggins.lua:58: bad argument #1 to 'unpack' (table expected, got nil)

```
I will open a PR with a fix.