AzureAiSearchEmbeddingStore - add "indexName" to the builder

[jdubois]

Fix #1062

[vprudnikov]

I assume the builder will ensure that either indexName or index is set but never both. Otherwise, it could be a bit hard to predict the implementation behavior.
If you agree then the test should verify this rule as well.

[jdubois]

Please have a look at my latest commit at ec7fd32 where I add a test for this

[vprudnikov]

looks good!

Since another comment is resolved now, I'll just write here my thoughts, however, you decide :)

I think it would be great to think about the following: What if someone else asks you to add one more option, e.g. 'eTag' or anything else?

• how much documentation will you update regarding what erases what and so on?
• how many NULLs / IFs / logical operators will appear in your code?
• will the complexity of the API increase or not?

If you think the builder API will be still OK, then this PR should be merged.

I got another idea of how it could look like from the client perspective.

AzureAiSearchEmbeddingStore.builder()
                .apiKey(properties.apiKey())
                .endpoint(properties.endpoint())
                .dimensions(1000)
//defaultSearchIndex() is a static method provided by AbstractAzureAiSearchEmbeddingStore
                .index(defaultSearchIndex().setName("myName"))
                .build();

However, the code above will probably struggle supporting dimensions.

One more approach:

AzureAiSearchEmbeddingStore.builder()
                .apiKey(properties.apiKey())
                .endpoint(properties.endpoint())
                .dimensions(1000)
//your implementation provides a template (pre-built SearchIndex) with all fields set, so developers will be able to modify it in the way they want by passing a Consumer<SearchIndex>
//As a result, the implementation won't suffer from additional NULLs/IF-checks/exceptions thrown.
                .index(indexTemplate -> indexTemplate.setName("myName"))
                .build();
```

[langchain4j]

@jdubois thank you a lot!