Make DenseVectorField codec agnostic

Currently, it is possible to set the parameter codecFormat in DenseVectorField. The only possible values are:

• Lucene91HnswVectorsFormat
• Lucene90HnswVectorsFormat

The DenseVectorField should be codec agnostic. The proposal is to remove any reference to the codec and introduce a reference to the algorithm instead. The only selectable algorithm is HNSW at the current state.

It should be still possible to customize the HNWS parameters:

• hnswMaxConn
• hnswBeamWidth