Weaviate document store schema mangled by enforced capitalization

[chrisk314]

Describe the bug
Weaviate document store schema mangled by enforced capitalization of schema class name. The class name specified in the Weaviate schema is capitalized in the WeaviateDocumentStore constructor which changes the casing of the class name. The resulting Weaviate schema is then inconsistent with the expected result of the class name exactly matching the input.

This is an overreach of responsibilities by the WeaviateDocumentStore constructor. It should not be mutating the user input. If the input is invalid, i.e., the class name does not start with a capital letter, then a ValueError should be raised instead.

To Reproduce
Pass a schema in the Weaviate collection settings with a class name in PascalCase such as CaseDocument. This results in a class being added to the Weaviate schema with the name Casedocument instead of CaseDocument as expected.

Describe your environment (please complete the following information):

• OS: Ubuntu-22.04 in WSL2
• Haystack version: 2.0.1
• Integration version: weaviate-haystack 2.0.0