[Store] Add InMemory

[Guikingone]

Q	A
Bug fix?	no
New feature?	yes
Docs?	yes
Issues	None
License	MIT

Hi 👋🏻

This PR aim to introduce an InMemoryStore to store vectors (mostly used for tests environments and/or POCs), the implementation is based around cosine similarity (others search algorithms can be used but will requires a dedicated interface like SearchStrategyInterface or other).

This store also allows to retrieve only a specific amount of items if required.

This store don't use initialize as everything is stored in an array.

PS: An optimized approach would be to use fpow but it requires 8.4 so ... Well, maybe for later 😄

[Nyholm]

Great idea. Thank you

[chr-hertel]

This is super cool - found only smaller items 👍

Thanks already @Guikingone!

[chr-hertel]

I think we could use array_push instead of iterating over all documents to add:

Suggested change

	foreach ($documents as $document) {
	$this->documents[] = $document;
	}
	array_push($this->documents, $documents);

see https://www.php.net/array_push

[chr-hertel]

named arguments don't add value here or do I miss something?

Suggested change

	callback: fn (VectorDocument $vectorDocument): array => [
	'distance' => $this->cosineSimilarity($vectorDocument, $vector),
	'document' => $vectorDocument,
	],
	array: $this->documents,
	fn (VectorDocument $vectorDocument): array => [
	'distance' => $this->cosineSimilarity($vectorDocument, $vector),
	'document' => $vectorDocument,
	],
	$this->documents,

[chr-hertel]

same for the others down below