…IPC (#4460)

Refs #3712 and #3713 (Linux and Windows tunnel process separation /
splitting)

This doesn't change the functionality of the GUI Client, but it adds a
boundary where:
- Windows can keep connlib in-process, so it stays stable during the
early phases of GA when I don't want to be fighting bugs caused by a big
architecture change
- Linux can move connlib into the tunnel process, which is required
before the Linux GUI Client reaches it own GA milestone

So it all looks redundant, because it's scaffolding until later this
year when both Linux and Windows are split. After that, some of this can
be removed.

…` which is the same thing (#4516)

Unfortunately I had to keep `linux-client` to get the compatibility
tests to pass. #4578 aims to remove that package.

Please add to this list if you think of anything:

```[tasklist]
# Things that may break that CI/CD won't catch
- [ ] Github release artifacts
- [ ] Knowledge base 
- [ ] Docker images
- [ ] Docker containers
- [ ] Existing `linux-client` users
- [ ] Anything that downloads ghcr artifacts
- [ ] Nix (Not sure if it's built in CI. It had a merge conflict)
```

Refs #4515, and #3712, #3782

I think this is what Thomas and I agreed on in Slack / Github

---------

Signed-off-by: Reactor Scram <[email protected]>
Co-authored-by: Thomas Eizinger <[email protected]>

)

Closes #4899

This has a known gap where theoretically the GUI could sign in while the
service is hung in startup, and then the service would wipe out the
GUI's DNS rules.

The workaround for that would be to restart the GUI, but in practice I
think the gap will not be hit, and it will go away once #3712 is done
anyway.

I tested it manually once using the reproduction steps from #4899 and it
worked.

…4978)

Ready for review.

Closes #3712.
Supersedes #4940.
Refs #4963.

I haven't figured out if it needs any new automated tests (unit,
integration, etc.) but the code itself is ready for review. There is
more refactoring that could be done, or could be left for later.

```[tasklist]
- [x] Move wintun setup from GUI to IPC service / headless client
- [x] Make sure the device ID is in a sensible place
- [x] Export IPC service logs in the zips
- [x] Test GUI + SC IPC service on Windows (f4db808 passed)
- [x] Make sure IPC service does not busy-loop
- [x] Test un-install checklist for Windows
- [x] Test upgrade checklist for Windows
- [x] Test GUI + systemd IPC service on Linux (c4ab7e7 passed)
- [x] Test upgrade checklist for Linux
- [x] Test un-install checklist for Linux
- [x] Make sure the IPC service logs out and deactivates DNS control if the GUI crashes
- [x] Test network changing
- [x] (it's intended behavior) ~~Look into spurious `on_update_resources` (fad86ba)~~
- [x] ~~Test max partition time on offline laptop~~ (I ended up just setting a 30-day default in the code)
- [x] Make sure headless Client does not busy-loop
- [x] Test standalone headless on Linux
- [ ] Add unit / integration tests
- [ ] Think about security a bit #3971
```

---------

Signed-off-by: Reactor Scram <[email protected]>
Co-authored-by: Jamil <[email protected]>