Make Pooling Parameterizable

[janheinrichmerker]

Currently, there are some hard-coded configurations and other issues in the pooling code:

• The Elasticsearch connection and index to get passage IDs by document ID are hard-coded
• Some paths are hard-coded.
• The set of retrieval models and re-rankers is hard-coded.

I believe we should move the configuration to the CLI options and ideally not directly rely on Elasticsearch at all (e.g., by directly retrieving from the segmented corpus).

[janheinrichmerker]

I addressed some of the issues in commits:

• 271f402
• 6afd729
• af0851d
• 54fa4f9
• c297147

[mam10eks]

Awesome, yes, makes sense.

I will modify this to be non-hard coded for the next iteration that I will create on friday