This is the first PR of issue #389. It addresses the bullets 1 and 3 listed in the issue.

• update matter_testing send_test_event_triggers to encode the endpoint from the --endpoint argument within the test event trigger
• update SDK implementation of the TestEventTriggerHandlers to account for endpoints
• implement an override flag (--use-legacy-test-event-triggers) in the test to allow sending test event triggers with EP0 for older devices - this shall be equivalent to "first endpoint" on the device, as it is handled now and will allow newer tests to be used with older devices
• add within-test documentation about test event triggers to enable debugging of both unimplemented and legacy test event triggers at the test event

This PR updates src/python_testing/matter_testing_infrastructure/chip/testing/matter_testing.py. It adds a validation in the send_test_event_triggers function. This function verifies if the user executed the test with the --use-legacy-test-event-triggers flag. If the flag is not set, then the event trigger variable will be updated with the --endpoint value as the [specification] (https://github.com/CHIP-Specifications/chip-test-plans/blob/master/src/testeventtrigger_overview.adoc) details. If the flag is set then the target endpoint remains as 0.

Testing

In the first terminal:

• Clear commissioning data:

  rm /tmp/chip_*

• Build light:

  ./scripts/build/build_examples.py –target linux-x64-all-clusters build

• Run:

  ./out/linux-x64-all-clusters/chip-all-clusters

In the second terminal:

• Activate Python environment
• Test:

  python3 src/python_testing/TC_DEM_2_2.py commissioning-method on-network --qr-code MT:-24J042C00KA0648G00

When running the test I added flags --endpoint <endpoint> and --use-legacy-test-event-triggers to check expected outcome.