Generate synthetic getter & setter descriptors for static properties in Java classes

(recognized as properties defined in classes without dispatchReceiver and extensionReceiver).
Fix 'when' generation for else-only case.

compiler/testData/ir/irText/expressions/whenElse.txt

@@ -0,0 +1,6 @@
+FILE /whenElse.kt
+  FUN public fun test(): kotlin.Int
+    BLOCK_BODY
+      RETURN type=kotlin.Nothing from=test
+        WHEN type=kotlin.Int operator=WHEN
+          else: CONST Int type=kotlin.Int value='42'