Rename test modules "array" and "render_basic" to avoid future name conflicts

Problem/Motivation

The test modules have been called eca_test_model_*. Two test modules, that don't have models but provide some plugins for tests are called eca_array and eca_render_basic. That could cause name conflicts in the future.

Proposed resolution

Let's rename them to eca_test_array and eca_test_render_basic.