Select interactively a coding system for the region FROM ... TO.
FROM can be a string, as in `write-region'.
CODINGS is the list of base coding systems known to be safe for this region,
typically obtained with `find-coding-systems-region'.
UNSAFE is a list of coding systems known to be unsafe for this region.
REJECTED is a list of coding systems which were safe but for some reason
were not recommended in the particular context.
DEFAULT is the coding system to use by default in the query.