ULTIMA8: Given items placed poorly in backpack

[OMGPizzaGuy]

Version 2.8.0 - In the original game, items given to the player are placed in good positions in the backpack. I believe these are not random locations. In ScummVM, the items always appear at the top left of the backpack, which is also not a valid position when moving them.

Mythan gives red potions and the recall item

[OMGPizzaGuy]

Updated to ensure item locations within containers are valid.
The recall item is still placed at top left, but this can be addressed at a future point if reported as another issue.

Candidate for backport. Fixed in commit:
​https://github.com/scummvm/scummvm/commit/bb4944cb673e9b8456d92542ecb0e1763e82b82d