Add $vectorSearch stage to Doctrine MongoDB ODM.

Prototype: https://github.com/GromNaN/symfony-celebrity-lookalike/blob/027426b3a584c278024324b74fde022ec8962a07/src/Doctrine/ODM/MongoDB/Aggregation/VectorSearchStage.php 

There is a strong relation between the $vectorSearch stage and the Vector Search index. It should be possible to automatically fill the "path" value from the index name, using the document VectorSearch metadata

->vectorSearch()
    ->index('faces')
    ->path('descriptionEmbeddings') // could be omitted
    ->numCandidates($limit * 20)
    ->queryVector($face->descriptionEmbeddings)
    ->limit($limit)

Question: is there a risk of confusion between limit parameter and the $limit stage in the fluent API ?

We can also create a #[VectorIndex] attribute that extend #[SearchIndex], promoting all the properties as main parameters.

#[ODM\VectorIndex(
    name: 'descriptions',
    numDimensions: 1024,
    path: 'descriptionEmbeddings',
    similarity: 'euclidean',
    filters: ['packages', 'tags'],
)]