pkgs/cli: Move the test folder inside the python module

Move the `tests` folder to `clan_cli/tests`.

As we now want part of our tests to live next to the functions that are
tested - tests that are not in the `/tests` module also need access to
the configured test fixtures that are exposed by the `pytest_plugins`
declaration.

The following folder structure doesn't support this model:

```
├── clan_cli
│   ├── api
│   │    └── api_init_test.py
├── tests/
│   ├── conftest.py
│   └── ...
```

Here `api_init_test.py` even when importing the test functions will not
have the fixtures configured.

There is a way to configure python to import the fixtures from another
[`project/module`](https://docs.pytest.org/en/stable/how-to/fixtures.html#using-fixtures-from-other-projects), but this seems to *generally* be discouraged.

So moving the `conftest.py` to the toplevel and the `/tests` folder into
the toplevel seems to be a sensible choice choice.

pkgs/clan-cli/clan_cli/tests/machines/vm1/default.nix

@@ -0,0 +1,21 @@
+{ config, ... }:
+{
+  clan.core.networking.targetHost = "__CLAN_TARGET_ADDRESS__";
+  system.stateVersion = config.system.nixos.release;
+  sops.age.keyFile = "__CLAN_SOPS_KEY_PATH__";
+  clan.core.facts.secretUploadDirectory = "__CLAN_SOPS_KEY_DIR__";
+  clan.virtualisation.graphics = false;
+
+  clan.core.facts.networking.zerotier.controller.enable = true;
+  networking.useDHCP = false;
+
+  systemd.services.shutdown-after-boot = {
+    enable = true;
+    wantedBy = [ "multi-user.target" ];
+    after = [ "multi-user.target" ];
+    script = ''
+      #!/usr/bin/env bash
+      shutdown -h now
+    '';
+  };
+}

pkgs/clan-cli/clan_cli/tests/machines/vm_with_secrets/default.nix

@@ -0,0 +1,21 @@
+{ config, ... }:
+{
+  clan.core.networking.targetHost = "__CLAN_TARGET_ADDRESS__";
+  system.stateVersion = config.system.nixos.release;
+  sops.age.keyFile = "__CLAN_SOPS_KEY_PATH__";
+  clan.core.facts.secretUploadDirectory = "__CLAN_SOPS_KEY_DIR__";
+  clan.virtualisation.graphics = false;
+
+  clan.core.networking.zerotier.controller.enable = true;
+  networking.useDHCP = false;
+
+  systemd.services.shutdown-after-boot = {
+    enable = true;
+    wantedBy = [ "multi-user.target" ];
+    after = [ "multi-user.target" ];
+    script = ''
+      #!/usr/bin/env bash
+      shutdown -h now
+    '';
+  };
+}

pkgs/clan-cli/clan_cli/tests/machines/vm_without_secrets/default.nix

@@ -0,0 +1,18 @@
+{ config, ... }:
+{
+  clan.core.networking.targetHost = "__CLAN_TARGET_ADDRESS__";
+  system.stateVersion = config.system.nixos.release;
+  clan.virtualisation.graphics = false;
+
+  networking.useDHCP = false;
+
+  systemd.services.shutdown-after-boot = {
+    enable = true;
+    wantedBy = [ "multi-user.target" ];
+    after = [ "multi-user.target" ];
+    script = ''
+      #!/usr/bin/env bash
+      shutdown -h now
+    '';
+  };
+}