Add a Jmeter test plan to show the performance testing process

[amrut-prabhu]

Description of feature/enhancement

• Add a Jmeter test plan sample that shows the various components involved in the performance test (eg. user authentication, param configs etc.).

Possible improvements to make after #9561 (in order of priority):

• Fail the test case if an Exception occurs - need to investigate whether this happens already
• Fail if there is a false value in the results file- fails based on thresholds set
• Since, we're using TestNG to run tests, ./gradlew lnpTests won't run the tests again, unless you make a change in the code. Investigate whether we should fix this behaviour since it is Performance testing (and not regression testing), and fix it if necessary.
• Refactor JmeterConfig to a builder class and add a default config.
• Change LNPTestData methods from abstract to implement the default behaviour return new HashMap<>();
• Delete result files (data files are already deleted) - need to discuss whether to do so
• Replace JSON_DATA_PATH and CSV_CONFIG_PATH with getClass().getSimpleName()?
• Don't write to a JSON file. Create class attribute LNPTestData#dataBundle instead. CSV generation can use this data.
  • If JSON file is still created: Preserve order of root keys in JSON data to match existing test data files. Use LinkedHashMap and convert to JSONObject (see here). One step further, preserve numerical order of dummy test data.