Remove hidden modifier from many reflect properties for better equality/rendering (#470)

pkl-core/src/test/kotlin/org/pkl/core/LanguageSnippetTestsEngine.kt

@@ -79,6 +79,9 @@ abstract class AbstractLanguageSnippetTestsEngine : InputOutputTestEngine() {
   // can't think of a better solution right now
   protected fun String.stripVersionCheckErrorMessage() =
     replace("Pkl version is ${Release.current().version()}", "Pkl version is xxx")
+  
+  protected fun String.stripStdlibLocationSha(): String =
+    replace("https://github.com/apple/pkl/blob/${Release.current().commitId()}/stdlib/", "https://github.com/apple/pkl/blob/\$commitId/stdlib/")
 }
 
 class LanguageSnippetTestsEngine : AbstractLanguageSnippetTestsEngine() {
@@ -142,7 +145,7 @@ class LanguageSnippetTestsEngine : AbstractLanguageSnippetTestsEngine() {
 
     val stderr = logWriter.toString()
 
-    return (success && stderr.isBlank()) to (output + stderr).stripFilePaths().stripWebsite()
+    return (success && stderr.isBlank()) to (output + stderr).stripFilePaths().stripWebsite().stripStdlibLocationSha()
   }
 }
 
@@ -220,6 +223,7 @@ abstract class AbstractNativeLanguageSnippetTestsEngine : AbstractLanguageSnippe
         .stripLineNumbers()
         .stripWebsite()
         .stripVersionCheckErrorMessage()
+        .stripStdlibLocationSha()
     } finally {
       process.destroy()
     }

stdlib/reflect.pkl

@@ -159,7 +159,7 @@ external const function TypeVariable(referent: TypeParameter): TypeVariable
 /// A program declaration.
 abstract external class Declaration {
   /// The source location of this declaration.
-  hidden location: SourceLocation
+  location: SourceLocation
 
   /// The documentation comment for this declaration, if any.
   docComment: String?
@@ -226,7 +226,7 @@ abstract external class TypeDeclaration extends Declaration {
 /// A class declaration.
 external class Class extends TypeDeclaration {
   /// The class reflected upon.
-  hidden reflectee: base.Class
+  reflectee: base.Class
 
   /// The type parameters of this class.
   ///
@@ -236,12 +236,12 @@ external class Class extends TypeDeclaration {
   /// The superclass of this class.
   ///
   /// All classes except [Any] have a superclass.
-  hidden superclass: Class?
+  superclass: Class?
 
   /// The supertype of this class.
   ///
   /// All classes except [Any] have a supertype.
-  hidden supertype: Type?
+  supertype: Type?
 
   /// The properties declared in this class.
   ///