IDM-10.4: Add PICS checks for events based on conformance and overrides

We have parsing for XmlEvent conformance in the clusters (https://github.com/project-chip/connectedhomeip/blob/master/src/python_testing/matter_testing_infrastructure/matter/testing/spec_parsing.py#L174), but don't check it in IDM-10.2 because the device doesn't expose event information.

We could do this in IDM-10.4 based on the PICS. It's far from ideal, but it's what we have.

Note that I haven't actually parsed out the event element overrides for device types (https://github.com/project-chip/connectedhomeip/blob/master/src/python_testing/matter_testing_infrastructure/matter/testing/spec_parsing.py#L195) because I couldn't do anything with them, but we could do the same thing there.

Cluster conformance would be similar to this, but with PICS: https://github.com/project-chip/connectedhomeip/blob/master/src/python_testing/test_testing/DeviceConformanceTests.py#L193

Device type overrides would be similar to this check, but against the PICS: https://github.com/project-chip/connectedhomeip/blob/master/src/python_testing/test_testing/DeviceConformanceTests.py#L423

Start with spec_parsing.py around the XmlEvent conformance parsing at lines 174 and 195, then compare the PICS-based cluster check in DeviceConformanceTests.py around line 193 and the device type override check around line 423. Implement IDM-10.4 checks for event conformance and device type overrides using PICS, and verify the relevant conformance tests pass.