This commit moves the TH structs and definitions to model. We don't want oohelperd to depend on web_connectivity@v0.4. Part of https://github.com/ooni/probe/issues/2240
Directory github.com/ooni/probe-cli/internal/cmd
This directory contains the source code for the CLI tools we build but we don't want to expose to the outside world. That is, you can only build these tools if you have cloned this repo.