fix: allow class body to end without newline after last method definition

In classDefinition in wren_compiler.c, add a check for TOKEN_RIGHT_BRACE before
requiring a newline after the last method definition, so that a closing brace
immediately following a method is accepted. Update test/class/syntax.wren with
a test case for this syntax.

test/class/syntax.wren

@@ -5,3 +5,7 @@ class A {}
 class B {
 
 }
+
+// No newline after last method.
+class C {
+  method {} }