Add MetadataFields auto configuration in AzureVectorStore

[Giurzo]

Expected Behavior

Be able to create an AzureVectorStore with specified MetadataFields list in the configuration, like:

spring:
  ai:
    vectorstore:
      azure:
        url: endpoint
        api-key: key
        metadata-fileds:
          - name: filterField
            fieldType: string

Current Behavior

Without specifying these MetadataFileds when creating the AzureVectorStore bean, it is not possible to filter a query by these fields, forcing the bean to be created manually (like here) without using the auto-configuration feature.

[markpollack]

@mkheck thoughts?

[mkheck]

@markpollack You can assign this one to me as well. I'll take a look at it and the other one and start working one, then the other.