[ObjCRuntime] Enable nullability in Runtime.CoreCLR.cs

[rolfbjarne]

And fix the resulting build errors+warnings.

[vs-mobiletools-engineering-service2]

📚 [PR Build] Artifacts 📚

Artifacts were not provided.

Pipeline on Agent XAMBOT-1042.Monterey'
Hash: 4518c9e94132606e05eaa6af7bc478bf8ce41aeb [PR build]

[vs-mobiletools-engineering-service2]

💻 [PR Build] Tests on macOS M1 - Mac Big Sur (11.5) passed 💻

✅ All tests on macOS M1 - Mac Big Sur (11.5) passed.

Pipeline on Agent
Hash: 4518c9e94132606e05eaa6af7bc478bf8ce41aeb [PR build]

[vs-mobiletools-engineering-service2]

🔥 [PR Build] Build failed 🔥

Build failed for the job 'Detect API changes'

Pipeline on Agent
Hash: $(GIT_HASH) [PR build]

[vs-mobiletools-engineering-service2]

🔥 Unable to find the contents for the comment: D:\a\1\s\change-detection\results\gh-comment.md does not exist :fire

Pipeline on Agent
Hash: 4518c9e94132606e05eaa6af7bc478bf8ce41aeb [PR build]

[vs-mobiletools-engineering-service2]

✅ API diff for current PR / commit

Legacy Xamarin (No breaking changes)

• iOS (no change detected)
• tvOS (no change detected)
• watchOS (no change detected)
• macOS (no change detected)

NET (empty diffs)

• iOS: (empty diff detected)
• tvOS: (empty diff detected)
• MacCatalyst: (empty diff detected)
• macOS: (empty diff detected)

✅ API diff vs stable

Legacy Xamarin (No breaking changes)

• iOS: vsdrops gist (No breaking changes)
• tvOS: vsdrops gist (No breaking changes)
• watchOS: vsdrops gist (No breaking changes)
• macOS: vsdrops gist (No breaking changes)

.NET (No breaking changes)

• iOS: vsdrops gist (No breaking changes)
• tvOS: vsdrops gist (No breaking changes)
• MacCatalyst: vsdrops gist (No breaking changes)
• macOS: vsdrops gist (No breaking changes)
• Microsoft.iOS vs Microsoft.MacCatalyst: vsdrops gist

Legacy Xamarin (stable) vs .NET

• iOS: vsdrops gist
• tvOS: vsdrops gist
• macOS: vsdrops gist

✅ Generator diff

Generator diff is empty

Pipeline on Agent
Hash: 4518c9e94132606e05eaa6af7bc478bf8ce41aeb [PR build]

[vs-mobiletools-engineering-service2]

🔥 [CI Build] Test results 🔥

Test results

❌ Tests failed on VSTS: simulator tests

0 tests crashed, 2 tests failed, 221 tests passed.

Failures

❌ bcl tests [attempt 3]

2 tests failed, 67 tests passed.

• [NUnit] Mono BCL tests group 1/tvOS - simulator/Debug: LaunchTimedOut
• [NUnit] Mono BCL tests group 2/tvOS - simulator/Debug: LaunchTimedOut

Html Report (VSDrops) Download

Successes

✅ cecil: All 1 tests passed. Html Report (VSDrops) Download
✅ dotnettests: All 1 tests passed. Html Report (VSDrops) Download
✅ fsharp: All 7 tests passed. Html Report (VSDrops) Download
✅ framework: All 8 tests passed. Html Report (VSDrops) Download
✅ generator: All 2 tests passed. Html Report (VSDrops) Download
✅ interdependent_binding_projects: All 7 tests passed. Html Report (VSDrops) Download
✅ install_source: All 1 tests passed. Html Report (VSDrops) Download
✅ introspection: All 8 tests passed. Html Report (VSDrops) Download
✅ linker: All 65 tests passed. Html Report (VSDrops) Download
✅ mac_binding_project: All 1 tests passed. Html Report (VSDrops) Download
✅ mmp: All 2 tests passed. Html Report (VSDrops) Download
✅ mononative: All 12 tests passed. Html Report (VSDrops) Download
✅ monotouch: All 23 tests passed. Html Report (VSDrops) Download
✅ msbuild: All 2 tests passed. Html Report (VSDrops) Download
✅ mtouch: All 1 tests passed. Html Report (VSDrops) Download
✅ xammac: All 3 tests passed. Html Report (VSDrops) Download
✅ xcframework: All 8 tests passed. Html Report (VSDrops) Download
✅ xtro: All 2 tests passed. Html Report (VSDrops) Download

Pipeline on Agent
Hash: 4518c9e94132606e05eaa6af7bc478bf8ce41aeb [PR build]

[rolfbjarne]

Test failures are unrelated (https://github.com/xamarin/maccore/issues/2450).