Support backcompat scenarios

[JoshLove-msft]

This is a parent issue that will contain the list of scenarios of backcompat scenarios we need to support. The implementation will leverage the "LastContractView" of the TypeProvider.

[JoshLove-msft]

Unable to add subissues from azure-sdk-for-net, but listing them here:

• https://github.com/Azure/azure-sdk-for-net/issues/49841
• https://github.com/microsoft/typespec/issues/7251
• https://github.com/Azure/typespec-azure/issues/1979
• • We want to compare the model factory method that we are going to generate against all model factory methods from the last contract view. If the only change is to the ordering of parameters, we would just use the last contract view method.

[JoshLove-msft]

The access of the LastContractView should have a check for the configuration flag. I think this will have to happen anyway as we need the ApiCompatVersion in order to load the last contract.

[JoshLove-msft]

Another scenario https://github.com/microsoft/typespec/issues/8287