Add support for KNN vector similarity search

[Pwuts]

Added components

• KNNExpression, to be passed to RedisModel.find(). Can be used in conjunction with normal operators, e.g.:

  v_query = openai.Embedding.create(input=query).data[0]["embedding"]
  v_query = numpy.array(v_query, numpy.float32)   # may be redundant
  
  MyRedisModel.find(
      MyRedisModel.prop == "value",
      knn=KNNExpression(
          k=5,
          vector_field=MyRedisModel.__fields__["embedding"],
          reference_vector=v_query.tobytes(),
      )
  )

• VectorFieldOptions, a simple dataclass to encapsulate the settings for a vector field; passed to Field(vector_options=.

Changed components

• JsonModel and HashModel, to accommodate vector fields
  • RedisModel.from_redis(), to add a field containing the vector score when applicable
• FindQuery, to incorporate KNN vector search support

[Pwuts]

@dvora-h @chayim 0:)

[Pwuts]

@chayim where should I add instructions for using this feature?

[chayim]

IMHO we should start a separate vectorsimilarity doc... @elena-kolevska given what you're up to - any preference?

[elena-kolevska]

Looping in @bsbodden, who's starting to work on a VSS quickstart for redis.io.

[Pwuts]

bump

[codecov-commenter]

Codecov Report

Patch coverage: 70.10% and project coverage change: -0.82 :warning:

Comparison is base (70f6401) 78.94% compared to head (583ae4a) 78.13%.

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Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #513 +/- ## ========================================== - Coverage 78.94% 78.13% -0.82% ========================================== Files 14 14 Lines 1178 1267 +89 ========================================== + Hits 930 990 +60 - Misses 248 277 +29 ``` | Flag | Coverage Δ | | |---|---|---| | unit | `78.13% <70.10%> (-0.82%)` | :arrow_down: | Flags with carried forward coverage won't be shown. [Click here](https://docs.codecov.io/docs/carryforward-flags?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=redis#carryforward-flags-in-the-pull-request-comment) to find out more. | [Impacted Files](https://app.codecov.io/gh/redis/redis-om-python/pull/513?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=redis) | Coverage Δ | | |---|---|---| | [aredis\_om/\_\_init\_\_.py](https://app.codecov.io/gh/redis/redis-om-python/pull/513?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=redis#diff-YXJlZGlzX29tL19faW5pdF9fLnB5) | `100.00% <ø> (ø)` | | | [aredis\_om/model/\_\_init\_\_.py](https://app.codecov.io/gh/redis/redis-om-python/pull/513?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=redis#diff-YXJlZGlzX29tL21vZGVsL19faW5pdF9fLnB5) | `100.00% <ø> (ø)` | | | [aredis\_om/model/model.py](https://app.codecov.io/gh/redis/redis-om-python/pull/513?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=redis#diff-YXJlZGlzX29tL21vZGVsL21vZGVsLnB5) | `85.30% <70.10%> (-1.79%)` | :arrow_down: |

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[XChikuX]

Okay, it's been more than a month. And this hasn't been merged even though all that's being corrected are type hints. @chayim, I'm aware you are a very busy individual. Please spare 5 minutes of your busy schedule for approving this!

[chayim]

Hi folks. I just merged in #534 so that we can have a CI that is properly reflective and runs this, and tests. That was the first step.

Logic wise, this looks proper, and as if it fits with the rest of this library. Merging in the master changes, and giving it another look.

I'm pro merging this - and issuing a release.