Improve OpenAPITool corner cases handling (missing operationId, servers under paths, etc)

[vblagoje]

Why:

Improves OpenAPITool's robustness in handling OpenAPI specifications with missing operationIds. Note: operationIds are not required but usually present, this fix handles openapi specs without operationIds

• fixes OpenAPITool fails to handle OpenAPI specs with servers under paths and missing operationId haystack#8035

What:

• Enhanced schema conversion to generate custom operationIds when they are missing
• Having operationIds simplifies operation resolution algorithm
• Updated type definitions and utility functions to support this change
• Add handling of servers field under path
• Expanded test suite to cover this new functionality

How:

• Implemented logic to create operationIds from path and HTTP method when they are absent:

  if "operationId" not in operation_spec:
      operation_spec["operationId"] = path_to_operation_id(path, http_method)

• Created integration tests with various API providers to ensure reliability

Testing:

• Unit tests for new operationId generation logic
• Integration tests with multiple LLM providers and external APIs

Notes for reviewer:

• Focus on operationId generation logic and its consistency with OpenAPI standards

[coveralls]

Pull Request Test Coverage Report for Build 9991860568

Warning: This coverage report may be inaccurate.

This pull request's base commit is no longer the HEAD commit of its target branch. This means it includes changes from outside the original pull request, including, potentially, unrelated coverage changes.

• For more information on this, see Tracking coverage changes with pull request builds.
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• For a quick fix, rebase this PR at GitHub. Your next report should be accurate.

Details

• 48 of 51 (94.12%) changed or added relevant lines in 4 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage increased (+0.7%) to 90.751%

---

Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
haystack_experimental/components/tools/openapi/types.py	12	13	92.31%
test/components/tools/openapi/test_openapi_tool.py	12	14	85.71%

Totals
Change from base Build 9957950977:	0.7%
Covered Lines:	1727
Relevant Lines:	1903

---

💛 - Coveralls

[vblagoje]

@shadeMe I removed @Amnah199 as this PR requires a lot of context uptake that you already have
cc @anakin87 as he discovered this particular case.

[shadeMe]

Let's also add a unit test that handles specs without operationIds.

[vblagoje]

Added also servers resolution unit test along with operationId - 🙏 @shadeMe