feat/Sharepoint Connector support for Entra-Id and Graph APIs

[kkr2320]

Is your feature request related to a problem? Please describe.
Currently Unstructured sharepoint connector using Sharepoint App Principal ( not Azure Entra ID) which is already end of product support from Microsoft ( but technically supported until spring-2026 ). Current setup does not meet the security standards established in most organizations.

Describe the solution you'd like
Sharepoint connector to use msal library and allow secure connections using certificate based authentication and use graph APIs to access Sharepoint Files and Folders. The same library can be used for One-Drive access as well.
Further specific Sharepoint connector should support access to both multi-tenants as well as Site Specific tenant libraries

Describe alternatives you've considered
N/A

Additional context
Response from Microsoft support
" If you create it as an Azure App Registration, then the only authentication mechanism allowed for SharePoint APIs would require a certificate. Otherwise, you'd require using Graph APIs for the ability to use a client secret alongside your Azure App Registration.

I can't speak to unstructured.io, but I'd recommend engaging them directly to see if they had any new implementations using Graph API. The requests in Graph are less resource intensive and are generally suggested over other SharePoint APIs. If no setup is available using Graph API, then you'll want to pursue creating the app registration as outlined above "