[bgen] Fix strong enums with value type backing fields.

[rolfbjarne]

We were generating the wrong code for strong enums backed by value type fields. We
thought the native symbol would be a pointer to the value, but it's the actual value
instead.

Also added a test to fetch all strong enum values using reflection.

This revealed that the UIAccessibilityTraits enum was bound incorrectly (wrong backing
type), so fix that. This required some compat code to not break binary compat.

[vs-mobiletools-engineering-service2]

✅ [CI Build #3bb7199] Build passed (Build packages) ✅

Pipeline on Agent
Hash: 3bb7199f90cc892e233c39de33ae1e79f6d6db58 [PR build]

[vs-mobiletools-engineering-service2]

✅ [PR Build #3bb7199] Build passed (Detect API changes) ✅

Pipeline on Agent
Hash: 3bb7199f90cc892e233c39de33ae1e79f6d6db58 [PR build]

[vs-mobiletools-engineering-service2]

✅ API diff for current PR / commit

.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 )

✅ API diff vs stable

.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 )

ℹ️ Generator diff

Generator Diff: vsdrops (html) vsdrops (raw diff) gist (raw diff) - Please review changes)

Pipeline on Agent
Hash: 3bb7199f90cc892e233c39de33ae1e79f6d6db58 [PR build]

[vs-mobiletools-engineering-service2]

✅ [CI Build #3bb7199] Build passed (Build macOS tests) ✅

Pipeline on Agent
Hash: 3bb7199f90cc892e233c39de33ae1e79f6d6db58 [PR build]

[vs-mobiletools-engineering-service2]

❌ [CI Build #3bb7199] Tests on macOS X64 - Mac Sonoma (14) failed ❌

Failed tests are:

• monotouch-test

Pipeline on Agent
Hash: 3bb7199f90cc892e233c39de33ae1e79f6d6db58 [PR build]

[vs-mobiletools-engineering-service2]

❌ [CI Build #3bb7199] Tests on macOS M1 - Mac Monterey (12) failed ❌

Failed tests are:

• monotouch-test

Pipeline on Agent
Hash: 3bb7199f90cc892e233c39de33ae1e79f6d6db58 [PR build]

[vs-mobiletools-engineering-service2]

💻 [CI Build #3bb7199] Tests on macOS arm64 - Mac Sequoia (15) passed 💻

✅ All tests on macOS arm64 - Mac Sequoia (15) passed.

Pipeline on Agent
Hash: 3bb7199f90cc892e233c39de33ae1e79f6d6db58 [PR build]

[vs-mobiletools-engineering-service2]

❌ [CI Build #3bb7199] Tests on macOS M1 - Mac Ventura (13) failed ❌

Failed tests are:

• monotouch-test

Pipeline on Agent
Hash: 3bb7199f90cc892e233c39de33ae1e79f6d6db58 [PR build]

[vs-mobiletools-engineering-service2]

🚀 [CI Build #60e4c12] Test results 🚀

Test results

✅ All tests passed on VSTS: test results.

🎉 All 118 tests passed 🎉

Tests counts

✅ cecil: All 1 tests passed. Html Report (VSDrops) Download
✅ dotnettests (iOS): All 1 tests passed. Html Report (VSDrops) Download
✅ dotnettests (MacCatalyst): All 1 tests passed. Html Report (VSDrops) Download
✅ dotnettests (macOS): All 1 tests passed. Html Report (VSDrops) Download
✅ dotnettests (Multiple platforms): All 1 tests passed. Html Report (VSDrops) Download
✅ dotnettests (tvOS): All 1 tests passed. Html Report (VSDrops) Download
✅ framework: All 2 tests passed. Html Report (VSDrops) Download
✅ fsharp: All 4 tests passed. Html Report (VSDrops) Download
✅ generator: All 5 tests passed. Html Report (VSDrops) Download
✅ interdependent-binding-projects: All 4 tests passed. Html Report (VSDrops) Download
✅ introspection: All 4 tests passed. Html Report (VSDrops) Download
✅ linker: All 44 tests passed. Html Report (VSDrops) Download
✅ monotouch (iOS): All 8 tests passed. Html Report (VSDrops) Download
✅ monotouch (MacCatalyst): All 11 tests passed. Html Report (VSDrops) Download
✅ monotouch (macOS): All 12 tests passed. Html Report (VSDrops) Download
✅ monotouch (tvOS): All 8 tests passed. Html Report (VSDrops) Download
✅ msbuild: All 2 tests passed. Html Report (VSDrops) Download
✅ windows: All 3 tests passed. Html Report (VSDrops) Download
✅ xcframework: All 4 tests passed. Html Report (VSDrops) Download
✅ xtro: All 1 tests passed. Html Report (VSDrops) Download

Pipeline on Agent
Hash: 60e4c12db5c6f95ca81108a72d6ffe1a264c2f53 [PR build]