add task.yml files for granite-3.1-8B-Instruct models

[derekk-nm]

SUMMARY:
adds task.yml config files for the models derived from ibm-granite/granite-3.1-8B-Instruct.
The task metric values are from the model card for the specific model (though the values for the "parent" come from the one of the RedHatAI models, where the evaluation accuracy table shows the measured parent metrics).

TEST PLAN:
All runs are initially showing failures. these are likely due to the fact that either the server or client do not have configuration settings set exactly as described in the model card's evaluation section.
Follow up runs were done w/ the relative tolerance (rtol) set for tasks that were too far off the default 0.04 setting. these need to be reviewed by research.

• ibm-granite/granite-3.1-8b-instruct accuracy ... follow up with new rtol and use 0.8.4 accuracy
• RedHatAI/granite-3.1-8b-instruct-quantized.w4a16 accuracy ... follow up with new rtol and use 0.8.4 accuracy
• RedHatAI/granite-3.1-8b-instruct-quantized.w8a8 accuracy ... follow up with new rtol and use 0.8.4 accuracy
• RedHatAI/granite-3.1-8b-instruct-FP8-dynamic accuracy ... follow up with new rtol for problem tasks accuracy