Access to localhost when building Extender Docker image

[AarrrBee]

@britzl

I use the “rebuild-and-run-standalone-local.sh” script to build and then run a server on my M1 Mac:

https://github.com/defold/extender/blob/dev/server/scripts/rebuild-and-run-standalone-local.sh

I started with that as it did look simpler, but it uses scripts in a git submodule (aws-build-tools) which isn’t public, and a previous discussion steered me towards the Docker approach.