Metadata filtering

[asg017]

References #26 , requires #123 and #122

Work-in-progress, needs more feature work, bug fixing, docs, and tests.

create virtual table vec_movies using vec0(
  movie_id integer primary key,
  synopsis_embedding float[1024],
  genre text,
  num_reviews int,
  mean_rating float
);

select
  movie_id,
  title,
  genre,
  num_reviews,
  mean_rating,
  distance
from vec_movies
where synopsis_embedding match '[...]'
  and genre = 'scifi'
  and num_reviews between 100 and 500
  and mean_rating > 3.5
  and k = 5;
/*
┌──────────┬─────────────────────┬─────────┬─────────────┬──────────────────┬──────────┐
│ movie_id │        title        │  genre  │ num_reviews │   mean_rating    │ distance │
├──────────┼─────────────────────┼─────────┼─────────────┼──────────────────┼──────────┤
│ 13       │ 'The Matrix'        │ 'scifi' │ 423         │ 4.5              │ 2.5      │
│ 18       │ 'Inception'         │ 'scifi' │ 201         │ 5.0              │ 2.5      │
│ 21       │ 'Gravity'           │ 'scifi' │ 342         │ 4.0              │ 5.5      │
│ 22       │ 'Dune'              │ 'scifi' │ 451         │ 4.40000009536743 │ 6.5      │
│ 8        │ 'Blade Runner 2049' │ 'scifi' │ 301         │ 5.0              │ 7.5      │
└──────────┴─────────────────────┴─────────┴─────────────┴──────────────────┴──────────┘