build: update Earthfile to be compatible with Earthly v0.8
We were using FROM +deps
a lot of times. In Earthly 0.8, subsequent
COPY commands would not copy from the root of the project but copy files
from that FROM
step. The required files would not be present there.
To make this clear, I've removed the FROM +deps
step and let every
task copy its own files. This makes it more explicit and easier to comprehend.
Issue: #32