distage-framework: Environment Variables aren't resolved in typesafe config files in RoleAppLauncher

[neko-kai]

reported by @DmytroOrlov

// file: common-reference.conf
logger {
  levels = {
    "warn" = ["org.http4s.blaze.channel.nio1.NIO1SocketServerGroup"]
  }
  json = false
  json = ${?LOG_JSON}
}

exception:

phase=early Failed to read logger config section, using defaults: exception=DecodingFailure(Boolean, List(DownField(json)))
DecodingFailure(Boolean, List(DownField(json)))

real cause:
splicing env vars in typesafe-config causes failures in circe-config boolean codec, because this converts bools to strings

[neko-kai]

Pushed workaround for the specific issue in https://github.com/DmytroOrlov/logstage-resolve , #871
But, properly fixing this for all cases requires #790