[CI] Build & Test Fabric iOS, Disable failing CircleCI checks

[Saadnajmi]

Please select one of the following

• I am removing an existing difference between facebook/react-native and microsoft/react-native-macos 👍
• I am cherry-picking a change from Facebook's react-native into microsoft/react-native-macos 👍
• I am making a fix / change for the macOS implementation of react-native
• I am making a change required for Microsoft usage of react-native

Summary

• Add a new job to build Fabric iOS on Azure Pipelines. While here, let's also rename the jobs to better reflect what they do
• Make some Fabric code fixes to get the new Fabric iOS job passing
• Disable the CircleCI tests that are failing while we are mid 0.71-merge

End result: Green CI checks 🎉

Changelog

[Type] [Added] - Build Fabric iOS on Azure Pipelines

Test Plan

CI passes

[christophpurrer]

To fix the current linking issue for

2023-01-14T08:17:33.4525870Z     Undefined symbol: _RNTMyNativeViewCls
2023-01-14T08:17:33.4526550Z     Testing cancelled because the build failed.

you should merge in #1520 first from @shwanton

[Saadnajmi]

To fix the current linking issue for

2023-01-14T08:17:33.4525870Z     Undefined symbol: _RNTMyNativeViewCls
2023-01-14T08:17:33.4526550Z     Testing cancelled because the build failed.

you should merge in #1520 first from @shwanton

I still get this error if RCT_NEW_ARCH_ENABLED is set. I spoke offline with @christophpurrer about it, and I'm going to chalk it up to "At this point in time in our repo, the new architecture / codegen are still experimental", and that flag enables more than fabric. I've decided to not set that flag to avoid that error.

[christophpurrer]

RCT_NEW_ARCH_ENABLED

I think for rn 0.68 you need to set USE_FABRIC ...
The flag RCT_NEW_ARCH_ENABLED wasn't used for Fabric afaik