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_host_groups_mutation.graphql

@@ -0,0 +1,28 @@
+### Mutation
+Use this mutation to import host groups.
+
+```graphql
+mutation ImportHostGroups($hostGroups: [CreateHostGroup!]!) {
+  importHostGroups(hostGroups: $hostGroups) {
+    groupName
+    groupid
+    message
+    error {
+      message
+      code
+      data
+    }
+  }
+}
+```
+
+### Variables
+```json
+{
+  "hostGroups": [
+    {
+      "groupName": "ConstructionSite/Test"
+    }
+  ]
+}
+```