feat/microsoft-sharepoint: add region parameter to MSSharePointRetriever

[SyedShahmeerAli12]

Summary

Closes #3673

• Added region: str | None = None init parameter to MSSharePointRetriever
• When set, the region field is included in the Microsoft Search API request body
• Required when using app-only (client credentials) authentication without it the API returns 400: Region is required when request with application permission
• Omitted from the request body when None (default), preserving existing delegated-auth behavior
• Serialized correctly via to_dict / from_dict

Test plan

• test_defaults asserts region is None by default
• test_to_dict asserts region: None in serialized output
• test_to_dict_with_region asserts region: "US" serializes correctly
• test_region_included_in_request_body_when_set verifies region appears in the HTTP POST body
• test_region_omitted_from_request_body_when_none —verifies region key is absent when not set
• TestLiveAppOnly integration test class for real app-only auth (skipped unless MS_SHAREPOINT_TENANT_ID, MS_SHAREPOINT_CLIENT_ID, MS_SHAREPOINT_CLIENT_SECRET env vars are set)
• All 81 unit tests pass
• Lint clean (ruff check + ruff format)

[github-actions]

Hi @SyedShahmeerAli12, thanks for your interest in contributing to Haystack! 🙏

⚠️ You currently have 4 open pull requests in this repository (#3565, #3483, #3254 and this one). Our review capacity is limited, so please hold off opening more PRs until we've had a chance to review your first 2 open PRs. This helps us give each contribution the attention it deserves. Thank you!

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[github-actions]

Heads-up for maintainers

This PR is from a fork and touches integrations whose integration tests require API keys.
Those tests are skipped in CI because fork PRs don't have access to repo secrets for security reasons.

Affected integrations:

• microsoft_sharepoint

Please run the integration tests locally (hatch run test:integration inside each folder) before approving.

[github-actions]

Coverage report (microsoft_sharepoint)

Click to see where and how coverage changed

File	Statements	Missing	Coverage	Coverage (new stmts)	Lines missing
integrations/microsoft_sharepoint/src/haystack_integrations/components/retrievers/microsoft_sharepoint
retriever.py
Project Total

This report was generated by python-coverage-comment-action

[bogdankostic]

Thanks @SyedShahmeerAli12! Looks good in general, just a few minor comments.

[bogdankostic]

Looks good, thanks for addressing the feedback so quickly @SyedShahmeerAli12!