backups: add clanCore backup & clan borgbackup module

checks/borgbackup/borg_test

@@ -0,0 +1,7 @@
+-----BEGIN OPENSSH PRIVATE KEY-----
+b3BlbnNzaC1rZXktdjEAAAAABG5vbmUAAAAEbm9uZQAAAAAAAAABAAAAMwAAAAtzc2gtZW
+QyNTUxOQAAACASG8CFZy8vrqA2erivzgnNUCuOkiBngt5lXPOXai2EMAAAAJAOOON0Djjj
+dAAAAAtzc2gtZWQyNTUxOQAAACASG8CFZy8vrqA2erivzgnNUCuOkiBngt5lXPOXai2EMA
+AAAEDTjUOWSYeU3Xu+Ol1731b9rXeEVXSdrhVOraA+7/35JBIbwIVnLy+uoDZ6uK/OCc1Q
+K46SIGeC3mVc85dqLYQwAAAADGxhc3NAaWduYXZpYQE=
+-----END OPENSSH PRIVATE KEY-----

checks/borgbackup/borg_test.pub

@@ -0,0 +1 @@
+ssh-ed25519 AAAAC3NzaC1lZDI1NTE5AAAAIBIbwIVnLy+uoDZ6uK/OCc1QK46SIGeC3mVc85dqLYQw lass@ignavia

checks/borgbackup/default.nix

@@ -0,0 +1,36 @@
+(import ../lib/container-test.nix) ({ ... }: {
+  name = "borgbackup";
+
+  nodes.machine = { self, ... }: {
+    imports = [
+      self.clanModules.borgbackup
+      self.nixosModules.clanCore
+      {
+        services.openssh.enable = true;
+        services.borgbackup.repos.testrepo = {
+          authorizedKeys = [
+            (builtins.readFile ./borg_test.pub)
+          ];
+        };
+      }
+      {
+        clanCore.machineName = "machine";
+        clanCore.clanDir = ./.;
+        clanCore.state."/etc/state" = { };
+        environment.etc.state.text = "hello world";
+        clan.borgbackup = {
+          enable = true;
+          destinations.test = {
+            repo = "borg@localhost:.";
+            rsh = "ssh -i ${./borg_test} -o StrictHostKeyChecking=no";
+          };
+        };
+      }
+    ];
+  };
+  testScript = ''
+    start_all()
+    machine.systemctl("start --wait borgbackup-job-test.service")
+    assert "machine-test" in machine.succeed("BORG_UNKNOWN_UNENCRYPTED_REPO_ACCESS_IS_OK=yes /run/current-system/sw/bin/borg-job-test list")
+  '';
+})