FIR: implement Java fields (in provider, type enhancement, scopes)

Related to KT-29218

compiler/testData/loadJava/compiledJava/TwoFields.fir.txt

@@ -1,2 +1,10 @@
 public final class TwoFields : R|java/lang/Object| {
+    public open property a(var): R|kotlin/Int|
+        public get(): R|kotlin/Int|
+        public set(value: R|kotlin/Int|): kotlin/Unit
+
+    public open property b(var): R|kotlin/Short|
+        public get(): R|kotlin/Short|
+        public set(value: R|kotlin/Short|): kotlin/Unit
+
 }