This change ensures that, in turn, we're able to "remote" all the traffic generated by the `geolocate` package, rather than missing some bits of it that were still using the standard library and caused _some_ geolocations to geolocate as the local host rather than as the remote host.
Extracted from https://github.com/ooni/probe-cli/pull/969, where we tested this functionality.
Closes https://github.com/ooni/probe/issues/1383 (which was long overdue).
Part of https://github.com/ooni/probe/issues/2340, because it allows us to make progress with that.
This is how I did it:
1. `git clone https://github.com/ooni/probe-engine internal/engine`
2. ```
(cd internal/engine && git describe --tags)
v0.23.0
```
3. `nvim go.mod` (merging `go.mod` with `internal/engine/go.mod`
4. `rm -rf internal/.git internal/engine/go.{mod,sum}`
5. `git add internal/engine`
6. `find . -type f -name \*.go -exec sed -i 's@/ooni/probe-engine@/ooni/probe-cli/v3/internal/engine@g' {} \;`
7. `go build ./...` (passes)
8. `go test -race ./...` (temporary failure on RiseupVPN)
9. `go mod tidy`
10. this commit message
Once this piece of work is done, we can build a new version of `ooniprobe` that
is using `internal/engine` directly. We need to do more work to ensure all the
other functionality in `probe-engine` (e.g. making mobile packages) are still WAI.
Part of https://github.com/ooni/probe/issues/1335
