KT-5524 Support [platformName] annotation for class members

@platformName is now supported for final non-overriding class member functions
(including property accessors).
Front-end provides diagnostics for inapplicable annotation cases.
Code generation updated:
- ignore kotlin.platform.platformName annotation for Java class methods;
- bridges generation generates proper JVM declarations in case of methods renamed with @platformName.
@platformName-related tests added.

#KT-5524 Fixed

compiler/testData/codegen/boxWithJava/platformName/FakePlatformName.java

@@ -0,0 +1,12 @@
+import kotlin.platform.platformName;
+
+public class FakePlatformName {
+    @platformName(name = "fake")
+    public String foo() {
+        return "foo";
+    }
+
+    public String fake() {
+        return "fake";
+    }
+}

compiler/testData/codegen/boxWithJava/platformName/FakePlatformName.kt

@@ -0,0 +1,6 @@
+fun box(): String {
+    val test1 = FakePlatformName().foo()
+    if (test1 != "foo") return "Failed: FakePlatformName().foo()==$test1"
+
+    return "OK"
+}