Support for Openapi.Net 2.0

[andrueastman]

Currently the library does not support breaking changes made in the Openapi.Net 2.0 library.

This causes Hidi to fail when transforming documents when using the Openapi.Net 2.0 library.

https://github.com/microsoft/OpenAPI.NET/blob/cb5bb2797a4a4aa61c96d4fd453ac5257474848d/src/Microsoft.OpenApi.Hidi/OpenApiService.cs#L423

[andrueastman]

Todo after resolving this and releasing Hidi

• revert fix: pin hidi version for now. microsoftgraph/msgraph-metadata#722
• revert fix: pin hidi version for now microsoftgraph/MSGraph-SDK-Code-Generator#1295
• revert https://github.com/microsoftgraph/msgraph-sdk-raptor/pull/3518

[baywet]

reverts:

• chore: unpins hidi microsoftgraph/MSGraph-SDK-Code-Generator#1306
• chore: reverts #722 microsoftgraph/msgraph-metadata#739