Refactor build process

[carlalexander]

Right now, I'm still using the Bref v1 build process which I got to work with the Docker buildx plugin and Depot using a base image on Docker hub. That said, I should look to migrate to the Bref v2 build process which removes the base image.

Right now, it's not possible to build the images without collaborator access to the base image. I also need to make Depot optional for the build.