* Refactor image builds to use buildx for multi arch image building
Signed-off-by: Rob Reus <rob@devrobs.nl>

* Adding image build sanity checks to Makefile
Signed-off-by: Rob Reus <rob@devrobs.nl>

* Making locally building of docker images possible
Signed-off-by: Rob Reus <rob@devrobs.nl>

* Adding docs on building container images using buildx
Signed-off-by: Rob Reus <rob@devrobs.nl>

* Adding changelog and implementing feedback from PR
Signed-off-by: Rob Reus <rob@devrobs.nl>

* Making GOPROXY used in the build containers configurable
Signed-off-by: Rob Reus <rob@devrobs.nl>