Add go.work, go.work.sum, and turn smartnode top level packages into modules

[jshufro]

The last piece in removing smartnode-install: porting the build to this repository.

The make release command builds all artifacts for a release, creates and tags docker containers, and creates and tags a docker manifest. I have not added docker push commands, as I think those should be executed cautiously, but we can add them if we want.

make release currently will make a directory structure a la:

build
├── 1.15.6
│   ├── cli
│   │   ├── rocketpool-cli-darwin-amd64
│   │   ├── rocketpool-cli-darwin-arm64
│   │   ├── rocketpool-cli-linux-amd64
│   │   └── rocketpool-cli-linux-arm64
│   └── daemon
│       ├── rocketpool-daemon-linux-amd64
│       └── rocketpool-daemon-linux-arm64
├── rocketpool-cli -> /home/jacob/rocketpool/smartnode/build/1.15.6/cli/rocketpool-cli-linux-amd64
└── rocketpool-daemon -> /home/jacob/rocketpool/smartnode/build/1.15.6/daemon/rocketpool-daemon-linux-amd64

but we can flatten it to behave more like smartnode-install if we want. This just feels more organized.