3 sampler interface between postgresql and manager

[AguirreNicolas]

Retrieve ConfigurableTask with its corresponding splits (in form of DictDataset) based on pocket-args like:

 {"task_name": {"address": "#########", "blacklist": [x, x, ..., x], "qty": k}

where:

• task_name: name of the task in terms of lm-eval-harness
• address: Pocket Network node address
• blacklist: Samples ids of the task_name already registerd.
• qty: Number of new random samples to test.