[AOT] Refactor SettingsLib/SettingsUI for Native AOT compatibility (#42644)

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fix/what does it change/how was it tested (even manually, if necessary)?
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## Summary of the Pull Request

Key Changes:

1. Settings.UI.Library:
- Added SettingsSerializationContext.cs with comprehensive
JsonSerializable attributes for all settings types
- Updated BasePTModuleSettings.ToJsonString() to use AOT-compatible
serialization
- Updated SettingsUtils.GetFile<T>() to use AOT-compatible
deserialization
- Modified all ToString() methods in Properties classes to use
SettingsSerializationContext
- Converted struct fields to properties in SunTimes and
MouseWithoutBordersProperties for serialization compatibility

2. Settings.UI:
- Fixed namespace alias in SourceGenerationContextContext.cs to avoid
conflicts

For any future developers who discover incorrect settings resolution,
please follow up my changes to add your setting type into
JsonSerilizerContext.



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## PR Checklist

- [ ] Closes: #xxx
- [ ] **Communication:** I've discussed this with core contributors
already. If the work hasn't been agreed, this work might be rejected
- [ ] **Tests:** Added/updated and all pass
- [ ] **Localization:** All end-user-facing strings can be localized
- [ ] **Dev docs:** Added/updated
- [ ] **New binaries:** Added on the required places
- [ ] [JSON for
signing](https://github.com/microsoft/PowerToys/blob/main/.pipelines/ESRPSigning_core.json)
for new binaries
- [ ] [WXS for
installer](https://github.com/microsoft/PowerToys/blob/main/installer/PowerToysSetup/Product.wxs)
for new binaries and localization folder
- [ ] [YML for CI
pipeline](https://github.com/microsoft/PowerToys/blob/main/.pipelines/ci/templates/build-powertoys-steps.yml)
for new test projects
- [ ] [YML for signed
pipeline](https://github.com/microsoft/PowerToys/blob/main/.pipelines/release.yml)
- [ ] **Documentation updated:** If checked, please file a pull request
on [our docs
repo](https://github.com/MicrosoftDocs/windows-uwp/tree/docs/hub/powertoys)
and link it here: #xxx

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## Detailed Description of the Pull Request / Additional comments

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Co-authored-by: Yu Leng <yuleng@microsoft.com>

src/settings-ui/Settings.UI/SerializationContext/SourceGenerationContextContext.cs

@@ -10,7 +10,7 @@ using System.Text.Json.Serialization;
 using System.Threading.Tasks;
 using Microsoft.PowerToys.Settings.UI.Helpers;
 using Microsoft.PowerToys.Settings.UI.Library;
-using Settings.UI.Library;
+using SettingsUILibrary = Settings.UI.Library;
 
 namespace Microsoft.PowerToys.Settings.UI.SerializationContext;
 
@@ -23,7 +23,7 @@ namespace Microsoft.PowerToys.Settings.UI.SerializationContext;
 [JsonSerializable(typeof(FileLocksmithSettings))]
 [JsonSerializable(typeof(FindMyMouseSettings))]
 [JsonSerializable(typeof(IList<PowerToysReleaseInfo>))]
-[JsonSerializable(typeof(LightSwitchSettings))]
+[JsonSerializable(typeof(SettingsUILibrary.LightSwitchSettings))]
 [JsonSerializable(typeof(MeasureToolSettings))]
 [JsonSerializable(typeof(MouseHighlighterSettings))]
 [JsonSerializable(typeof(MouseJumpSettings))]