Add WLM support to the SmartRedis testing system

[billschereriii]

Description

Step 5 in the SmartRedis test/build rework, this step reworks the test subsystem add support for WLMs.

Justification

When complete, the test/build refactor will be a huge quality of life improvement for developers and users alike.

This step will simplify testing on supers as well as enabling nightly tests in these environments.

Implementation Strategy

As documented in the SmartRedis build spike design document

Completion criteria

• Add support to the Redis launch/teardown script for WLMs: obtaining allocations and launching of tests to backend nodes
• Add support for SR_TEST_WLM, SR_TEST_ALLOC_COMMAND, SR_TEST_ALLOC_FLAGS, SR_TEST_LAUNCH_COMMAND, and SR_TEST_LAUNCH_FLAGS variables to Makefile and Redis launch/teardown script
• Update documentation with new testing capabilities and examples