Spring-ai Simplify the VectorStore#similaritySearch signature

Currently the VectorStore interface offers at least 5 variations of the similaritySearch() method, each with different set of arguments.

We should collapse all methods into a single similaritySearch(SearchRequest req) using a convenient SearchRequest builder like:

vectorStore.similaritySearch(
    SearchRequest.query("Hello World")
    .withTopK(5)
    .withSimilarityThreshold(0.6)
    .withFilterExpression("country == 'UK"));

Comment From: tzolov

Resolved at 952ff6c3197a955e5d0d57df459d26f23dd8ebc6