Enable usage of previously backed up settings when starting new ACA container

[iadgovuser29]

An environment variable can be given to the container that will cause the startup scripts to use backup settings rather than generate new ones on container launch.

Mount the settings to a location within the container and give the environment variable HIRS_USE_IMPORTED_ETC_HIRS the path to the mountpoint within the container to look for those settings.

If the container doesn't already have settings defined, it will ingest the files under that mountpoint- copy them to the default settings folder and reset permissions necessary for container services to read them.

The files on the host will not be affected.

Example usage from a linux ACA:

docker cp <existingaca>:/etc/hirs /backupOnHost
docker run -p 8443:8443 -v /backupOnHost:/backupInNewContainer -e HIRS_USE_IMPORTED_ETC_HIRS=/backupInNewContainer -dit ghcr.io/nsacyber/hirs/aca