Story Arcs: Add images for existing personnel

[AaronGullickson]

I need to figure out how to assign a character image from the story arc to a personnel member in the campaign.

[AaronGullickson]

It seems that with the ability for users to now create their custom data directory, it should be possible to direct the search for character images to the subdirectories of story arcs.

[AaronGullickson]

Note that ideally this would also allow loading those images directly into botForce units. The examples from the Young Wolves tracks will be Phelan and Vlad who will be fighting in some scenarios as allies of the player.

[AaronGullickson]

This will be enabled when PR MegaMek/megamek#5266 is merged into MegaMek.

[AaronGullickson]

Now merged.