plugins/neotest-ctest: add neotest-ctest adapter

tests/test-sources/plugins/by-name/neotest/ctest.nix

@@ -0,0 +1,23 @@
+{
+  example = {
+    plugins = {
+      treesitter.enable = true;
+      neotest = {
+        enable = true;
+
+        adapters.ctest = {
+          enable = true;
+
+          settings = {
+            is_test_file.__raw = ''
+              function(file_path)
+                -- check if path has test in it
+                return string.match(file_path, "test") ~= nil
+              end
+            '';
+          };
+        };
+      };
+    };
+  };
+}