[XABT] Fix ApplicationAttribute.ManageSpaceActivity manual mapping (#9708)

[jonpryor]

Fixes: #9705

Context: 3ab74db

When converting AndroidManifest.xml attribute mappings in 3ab74db, ApplicationAttribute.ManageSpaceActivity was not correctly mapped in the manual mapping.

The result is that if the property is used:

[assembly: Application(ManageSpaceActivity=typeof(MyManageSpaceActivity))]

the build will fail:

error XAGJS7007: System.InvalidCastException: Unable to cast object of type 'System.String' to type 'System.Type'.
error XAGJS7007:    at Android.App.ApplicationAttribute.<>c.<AddManualMapping>b__189_3(ApplicationAttribute self, Object value) in /Users/runner/work/1/s/xamarin-android/src/Xamarin.Android.Build.Tasks/Mono.Android/ApplicationAttribute.Partial.cs:line 47
error XAGJS7007:    at Xamarin.Android.Manifest.ManifestDocumentElement`1.Load(T value, CustomAttribute attribute, TypeDefinitionCache cache) in /Users/runner/work/1/s/xamarin-android/src/Xamarin.Android.Build.Tasks/Utilities/ManifestDocumentElement.cs:line 127
error XAGJS7007:    at Android.App.ApplicationAttribute.FromCustomAttributeProvider(ICustomAttributeProvider provider, TypeDefinitionCache cache) in /Users/runner/work/1/s/xamarin-android/src/Xamarin.Android.Build.Tasks/Mono.Android/ApplicationAttribute.Partial.cs:line 67
error XAGJS7007:    at Xamarin.Android.Tasks.ManifestDocument.CreateApplicationElement(XElement manifest, String applicationClass, List`1 subclasses, TypeDefinitionCache cache) in /Users/runner/work/1/s/xamarin-android/src/Xamarin.Android.Build.Tasks/Utilities/ManifestDocument.cs:line 581
error XAGJS7007:    at Xamarin.Android.Tasks.ManifestDocument.Merge(TaskLoggingHelper log, TypeDefinitionCache cache, List`1 subclasses, String applicationClass, Boolean embed, String bundledWearApplicationName, IEnumerable`1 mergedManifestDocuments) in /Users/runner/work/1/s/xamarin-android/src/Xamarin.Android.Build.Tasks/Utilities/ManifestDocument.cs:line 290
error XAGJS7007:    at Xamarin.Android.Tasks.GenerateJavaStubs.MergeManifest(NativeCodeGenState codeGenState, Dictionary`2 userAssemblies) in /Users/runner/work/1/s/xamarin-android/src/Xamarin.Android.Build.Tasks/Tasks/GenerateJavaStubs.cs:line 363
error XAGJS7007:    at Xamarin.Android.Tasks.GenerateJavaStubs.Run(Boolean useMarshalMethods) in /Users/runner/work/1/s/xamarin-android/src/Xamarin.Android.Build.Tasks/Tasks/GenerateJavaStubs.cs:line 270
error XAGJS7007:    at Xamarin.Android.Tasks.GenerateJavaStubs.RunTask() in /Users/runner/work/1/s/xamarin-android/src/Xamarin.Android.Build.Tasks/Tasks/GenerateJavaStubs.cs:line 102
error XAGJS7007:    at Microsoft.Android.Build.Tasks.AndroidTask.Execute() in /Users/runner/work/1/s/xamarin-android/external/xamarin-android-tools/src/Microsoft.Android.Build.BaseTasks/AndroidTask.cs:line 25

ApplicationAttribute.ManageSpaceActivity needs to follow the pattern other attributes of type Type follow, like ActivityAttribute.ParentActivity:

mapping.Add (
	member: "ParentActivity",
	attributeName: "parentActivityName",
	getter: self => self._ParentActivity,
	setter: (self, value) => self._ParentActivity = (string) value,
	typeof (Type)
);

With this change, the reported case in #9705 generates the proper AndroidManifest value:

<application android:manageSpaceActivity="crc64fe9411caa440e724.MyManageSpaceActivity" … >

[dellis1972]

Looks good, but needs a unit test.

[jonathanpeppers]

Since we didn't add a test in #9708 (this one is a backport), it's probably ok to merge this one without a test.