feat: build and package Apisix for Docker Alpine.

[Kushal-kothari]

Alpine images will drastically shrink the image size and network cost and have our services start faster. We are planning to extend alpine image to all since some images are based on alpine already.

Any feedback and suggestions are welcome :)

[Kushal-kothari]

Assigning myself @Kushal-kothari

[imjoey]

@Kushal-kothari Hi, thanks for your idea. I noticed that apache/apisix-docker already provides the alpine version of docker-compose, see https://github.com/apache/apisix-docker/blob/master/example/docker-compose-alpine.yml. Can you have a look and make this issue more clear what we should do then? Thanks.