feat: add comprehensive tests and samples for host and user rights endpoints

- Added GraphQL sample queries and mutations for host and user rights endpoints in the 'docs' directory.

- Implemented unit tests for all remaining GraphQL endpoints, including hosts, devices, host groups, locations, and user permissions.

- Created dedicated integration tests for host and user rights workflows, utilizing the new sample files.

- Fixed a bug in 'HostImporter.getHostGroupHierarchyNames' to correctly process and sort nested host group hierarchies.

- Refined Zabbix API mocking in tests to improve reliability and support path-based routing.

- Verified all 38 tests across 11 suites pass successfully.

docs/sample_import_user_rights_mutation.graphql

@@ -0,0 +1,50 @@
+### Mutation
+Use this mutation to import user rights (roles and groups).
+
+```graphql
+mutation ImportUserRights($input: UserRightsInput!, $dryRun: Boolean) {
+  importUserRights(input: $input, dryRun: $dryRun) {
+    userRoles {
+      id
+      name
+      message
+    }
+    userGroups {
+      id
+      name
+      message
+    }
+  }
+}
+```
+
+### Variables
+```json
+{
+  "input": {
+    "userRoles": [
+      {
+        "name": "Test Role",
+        "type": 1,
+        "rules": {
+          "api_access": 1,
+          "api": ["host.get", "item.get"]
+        }
+      }
+    ],
+    "userGroups": [
+      {
+        "name": "Test Group",
+        "gui_access": 0,
+        "hostgroup_rights": [
+          {
+            "name": "ConstructionSite/Test",
+            "permission": "READ_WRITE"
+          }
+        ]
+      }
+    ]
+  },
+  "dryRun": false
+}
+```