feat: Add a Azure OCR Converter that uses the azure-ai-documentintelligence library

[sjrl]

The AzureConverter (in Haystack v1) and the AzureOCRConverter (in Haystack v2) use the azure-ai-formrecognizer package. A new package azure-ai-documentintelligence has been released about 8 months ago that is meant to replace the former. We should migrate to the new package since it offers new features and will be the one Microsoft continues to support moving forward.

For example the new package supports the returning a file (using the prebuilt-layout model) in Markdown format. See details here. This was explicitly added by Microsoft to better support passing the OCR output to LLMs.

Here are other add-on capabilities: https://learn.microsoft.com/en-us/azure/ai-services/document-intelligence/concept-add-on-capabilities?view=doc-intel-4.0.0&tabs=rest-api#high-resolution-extraction

Pricing is more expensive when using add-on capabilities (e.g. OCR High Resolution): https://azure.microsoft.com/en-au/pricing/details/ai-document-intelligence/