Fix #4019: Recognize with expressions whose initializer awaits

Roslyn spills the receiver of an initializer assignment that precedes an
await into a hoisted temporary, so the clone of a with expression (and the
object of an object initializer) reaches the initializer transform through
a copy it rejects. Only copies between two hoisted compiler temporaries are
inlined: folding copies of hoisted user locals as well would turn a user's
local into an initializer.

ICSharpCode.Decompiler.Tests/TestCases/Pretty/Records.cs

@@ -3,6 +3,7 @@ using System;
 using System.Runtime.InteropServices;
 using System.Text;
 #endif
+using System.Threading.Tasks;
 
 namespace ICSharpCode.Decompiler.Tests.TestCases.Pretty
 {
@@ -129,6 +130,19 @@ namespace ICSharpCode.Decompiler.Tests.TestCases.Pretty
 					}
 				};
 			}
+			public async Task<PrimaryCtor> WithAwait(PrimaryCtor input)
+			{
+				return input with {
+					A = await Task.FromResult(42)
+				};
+			}
+			public async Task<Fields> WithAwaitAfterConstant(Fields input)
+			{
+				return input with {
+					A = 42,
+					B = await Task.FromResult(3.141)
+				};
+			}
 		}
 
 		public abstract record WithNestedRecords