Closes#5063, supersedes #5850
Other refactors and changes made as part of this:
- Adds the ability to disable DNS control on Windows
- Removes the spooky-action-at-a-distance `from_env` functions that used
to be buried in `tunnel`
- `FIREZONE_DNS_CONTROL` is now a regular `clap` argument again
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Signed-off-by: Reactor Scram <ReactorScram@users.noreply.github.com>
Is this worth it?
```[tasklist]
### Before merging
- [x] Double-check docs and ask Jamil to review
- [x] Would need Brian to review the terraform thing
- [x] Make sure Docker compat isn't broken for existing users (shouldn't be, the image is still just `client`)
- [x] Decide whether compatibility tests need to pass (if something breaks after merge we can revert this)
```
For tests it doesn't hurt, but this will be used as a template for the
systemd service we ship to production, and that can't have the ID there.
So I'm also cleaning up a few other problems I noticed:
- I wanted to split the service files as part of #4531, so that the GUI
Client and headless Client can have separate sandbox rules. e.g, the
headless Client won't be allowed to create Unix domain sockets
- I'm punting more things to systemd, which allows us to tighten down
the sandbox further, e.g. creating `/var/lib/dev.firezone.client` and
`/run/dev.firezone.client` for us
- Closes#4461
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Signed-off-by: Reactor Scram <ReactorScram@users.noreply.github.com>
