Feat(pkg/e3): Complete testing for E3 client code.

Chore(e3/defaultDepth/redirect): Slight changes. Moving things around.

Feat(go.mod): Dependency cleanup. Removed some.

Feat(private files): Upload files to E3 as private.

Feat(e3): Making E3 integration better. Adding tests. Potentially use as
future ref to pointer users toward to help them implement E3.

WIP(*): Project init.