Add E2E Testing for Matrix

1) TestPipelineRunMatrixed is an integration test that verifies that a Matrixed PipelineRun succeeds with both `matrix params` and `matrix include params`. It also tests array indexing and whole array replacements by consuming results produced by other PipelineTasks.

2) TestPipelineRunMatrixedFailed is an integration test with a Matrixed PipelineRun that contains 2 successful, and 1 unsucessful TaskRun. This test verifies that the 3rd task run failing will cause the PipelineRun to fail, however the first 2 TaskRuns should succeed before the last one fails.