Implement term dependence model

[lintool]

We probably also want to implement some type of phrasal query model... SDM seems like a good start.

[dyshi]

https://github.com/dyshi/Anserini/tree/feature-implement-sdm

I have a simple implementation tested on the Gov2 collection maybe we can merge this into the feature extractor branch after?

[Peilin-Yang]

It turns out that we can combine different query semantics from Lucene to construct SDM query.
For example, for ordered window and unordered window query, we can use SpanQuery.
We then use BooleanQuery together with BoostQuery to construct the complete query.

[Peilin-Yang]

Merged as #359