enhancement - lightweight the bootstrap process

[MetaBarj0]

Today, one can bootstrap its system with carrier using the following command :
carrier bootstrap run
The purpose of this issue is not to change how the bootstrap run is invoked but how it performs.
Today it is kind of heavy :

• relies on the base/archlinux docker image, that is far to be lightweight
• this image needs to be updated and various software must be installed before building any sources that is time and bandwidth consuming
• gcc (currently 7.2.0 and 7.3.0) that are the only supported versions so far must be cross-compiled to be useable with musl-libc
• an alpine image with a docker installation is needed to create the metabarj0/docker-cli image therefore, the base/archlinux image is not the only one base image the bootstrap process needs.

Once this issue will be solved, the bootstrap process should rely only on the alpine docker image :

• very lightweight image
• already based on musl-libc (though maybe not the latest version)
• won't change anything for the metabarj0/docker-cli image creation