Add offline apt package cache in kube runtime

[hzy46]

Runtime plugins use apt update and apt install ... to install some additional packages. If the network connection from pai cluster to the apt repository is poor, apt install may take a long period of time or even fail.

Since we use kube runtime to initialize the environment before job container, it is possible to use the runtime container as a "cache" of some frequently-needed packages. Here is one possible solution in detail:

• When we build runtime container, add all .deb files relied by certain package and certain os version. It could be achieved by the following commands:

apt-get update
apt-get -y install --print-uris package-name | cut -d\' -f2 | grep http:// > apturls
wget -i <path-to-apturls-file> 

• In every runtime plugin, if it needs some package, use the pre-downloaded .deb files to install it.