[generator] Process Javadoc for nested types (#996)

Fixes: #992
Looking at the latest set of API docs for [a nested type][0] I noticed
that we were missing a lot of content that should have been produced by
the Mono.Android build when translating Javadoc to C# doc comments.
After further investigation, we realized that we were not attempting to
process and translate Javadoc for _any_ nested types.
Fix this oversight by adding a missing Javadoc processing iteration
over each type's nested types.
Additionally, Java documentation URLs for nested types have been fixed
by replacing `$` with `.` in both the URL and text for the URL. This
replaces the previous URL of e.g.
https://developer.android.com/reference/android/accessibilityservice/AccessibilityButtonController$AccessibilityButtonCallback
with:
https://developer.android.com/reference/android/accessibilityservice/AccessibilityButtonController.AccessibilityButtonCallback
[0]: https://github.com/xamarin/android-api-docs/blame/b4084443c0354661e2257eb698e03d3fe1d86f1b/docs/Mono.Android/en/Android.AccessibilityServices/AccessibilityButtonController%2BAccessibilityButtonCallback.xml#L25

Author: pjcollins

tools/generator/Java.Interop.Tools.Generator.ObjectModel/JavadocInfo.cs

@@ -257,9 +257,10 @@ static XElement CreateAndroidDocLinkUri (string prefix, string declaringJniType,
 // Example: "https://developer.android.com/reference/android/app/Application#registerOnProvideAssistDataListener(android.app.Application.OnProvideAssistDataListener)"
 // Example: "https://developer.android.com/reference/android/animation/ObjectAnimator#ofFloat(T,%20android.util.Property%3CT,%20java.lang.Float%3E,%20float...)"
 
+declaringJniType=declaringJniType.Replace("$",".");
 varjava=newStringBuilder(declaringJniType)
-.Replace("/",".")
-.Replace("$",".");
+.Replace("/",".");
+
 varurl=newStringBuilder(prefix);
 if(!prefix.EndsWith("/",StringComparison.Ordinal)){
 url.Append("/");

tools/generator/Java.Interop.Tools.Generator.Transformation/JavadocFixups.cs

@@ -46,6 +46,9 @@ public static void Fixup (List<GenBase> gens, CodeGeneratorOptions options)
 
 foreach(vartypeingens){
 AddJavadoc(type,typeJavadocs,options.XmldocStyle);
+foreach(varnestedintype.NestedTypes){
+AddJavadoc(nested,typeJavadocs,options.XmldocStyle);
+}
 }
 }