Provide different sorting options under Formation menu

From Discord by faerghast:

perhaps some nuance to the character list in maps could be a good QoL addition as well? the character list is organized chronologically of recruits
eden first, francisco, leon etc
down to albrecht currently
however say i want to undeploy robere, what if i just hate using robere altogether and i benched him day one
in the battle prep, he'll still be at the top, taking space away from characters i may actually be using, this is more noticeable for a character like Dane, who was recruited later, and requires me to scroll down