[Observation] Member properties that have visibility attributes should rename using trailing trivia (#65812)

Author: phausler

lib/Macros/Sources/ObservationMacros/ObservableMacro.swift

@@ -95,7 +95,7 @@ extension DiagnosticsError {
 
 extension ModifierListSyntax {
   func privatePrefixed(_ prefix: String) -> ModifierListSyntax {
-    let modifier: DeclModifierSyntax = DeclModifierSyntax(name: "private")
+    let modifier: DeclModifierSyntax = DeclModifierSyntax(name: "private", trailingTrivia: .space)
     return ModifierListSyntax([modifier] + filter {
       switch $0.name.tokenKind {
       case .keyword(let keyword):

test/stdlib/Observation/Observable.swift

@@ -28,6 +28,11 @@ class ContainsWeak {
   weak var obj: AnyObject? = nil
 }
 
+@Observable
+public class PublicContainsWeak {
+  public weak var obj: AnyObject? = nil
+}
+
 @Observable
 class ContainsUnowned {
   unowned var obj: AnyObject? = nil