[FEA] Metadata pre-filtered search

Filtered search for a more general type of label data is needed for many use cases. Typically, this takes the form of a vector of integers for every vector in the dataset and query. The general predicate function approach implemented in search_with_filter can be used for this, but is not currently exposed in the header for CAGRA. As a work-around, the source file with "search_with_filtering" can be included directly, but this greatly increases compile time and is not ideal.

If it is simpler or more performant, another option is a less general "labeled" search option where a specific format of label data can be provided to perform filtered search this way. Something like this could satisfy most use cases and may be preferable to a completely general predicate function.

Start with the existing search_with_filter implementation and the CAGRA public header, then compare exposing its general predicate function with adding the proposed labeled-search option. Done means metadata-based filtered search is available through the public API without directly including the source file, with the preferred approach and expected behavior documented by the implementation and tests.