Cover dynamic bitwise, shift, and modulo compound assignments

The pretty DynamicTests only exercised += -= *= /= on a dynamic target, leaving
%= &= |= ^= <<= >>= unverified even though VisitDynamicCompoundAssign and
GetAssignmentOperatorTypeFromExpressionType already map them. Add them so the
full set of dynamic compound-assignment operators is pinned by a round-trip
test.

Assisted-by: Claude:claude-opus-4-8:Claude Code

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

@@ -369,6 +369,12 @@ namespace ICSharpCode.Decompiler.Tests.TestCases.Pretty
 			a.Setter2 -= b;
 			a.Setter2 *= b;
 			a.Setter2 /= b;
+			a.Setter2 %= b;
+			a.Setter2 &= b;
+			a.Setter2 |= b;
+			a.Setter2 ^= b;
+			a.Setter2 <<= b;
+			a.Setter2 >>= b;
 			field.Setter += 5;
 			field.Setter -= 5;
 		}