move functions from docker to es-build

[thomasreichmann]

Move to using es-build + layers with makefile. There is no need to use docker in this instance, if we want we could keep docker running on the lambdas that use ffmpeg, but even then I still believe that we get the same amount of control and ease of use by getting ffmpeg through a lambda layer.

es-build will also nullify the cost of storing the docker images on a private ECR repo.