Add multi-line support to entrypoint.sh

[jefkel]

This PR adds some specific multi-line secret support to the release-1.2 branch by using wc to detect when a secret is multi-line and adding the expected | before adding the secret contents.

/usr/bin/wc from bin-utils
/usr/bin/sed from sed

The same (or similar) fix may work in the 1.3 or master branches to replace the following:

apb-base/files/usr/bin/entrypoint.sh

Line 65 in 6064ac4

echo "$file: $(cat ${SECRETS_DIR}/${key}/..data/${file})" >> $PASSWORDS

However, I haven't done any testing on those branches.