Improved multi-arch support

This is needed for better experience on various platforms.

Issues:
* On Apple silicon builds takes much more time because of overhead incurred by emulation of amd64 on aarch64.
* Deployment to clusters with architecture not matching the architecture of developers machine:
the image build on developer machine might not run in the cluster or it can run but with high performance penalty.

First step is to offer multi-arch builder images, this should ensure good build times on various developer machines.
* For `s2i` there is noting to do, images are already supporting `amd64`, `aarch64`, `ppc64le` and `s390x`.
* For `buildpacks` we depend on `pakteo-buildpacks` project to provide multi-arch images.

Second step is to allow user to choose architecture(s) of the image produced by `func build`, this ensues that images produced on developer machine would run in the cluster. This could be done by some flag or config value in `func.yaml` or some global config.