Add SIR builder and printer for classes #KT-65905 fixed

Merge-request: KT-MR-14478
Merged-by: Artem Olkov <artem.olkov@jetbrains.com>

native/swift/swift-export-standalone/testData/classes/input_root/classes.kt

@@ -0,0 +1,4 @@
+
+class Foo {
+    class INSIDE_CLASS // this should be ignored currently
+}

native/swift/swift-export-standalone/testData/classes/input_root/should_be_ignored.kt

@@ -0,0 +1,28 @@
+public annotation class OptIn
+
+enum ENUM {
+    class INSIDE_ENUM
+}
+
+interface OUTSIDE_PROTO {
+    class INSIDE_PROTO
+}
+
+class INHERITANCE_COUPLE : OUTSIDE_PROTO.INSIDE_PROTO, OUTSIDE_PROTO
+class INHERITANCE_SINGLE_PROTO : OUTSIDE_PROTO.INSIDE_PROTO
+
+open class OPEN_CLASS
+
+class INHERITANCE_SINGLE_CLASS : OPEN_CLASS
+
+object OBJECT
+
+data class DATA_CLASS(val a: Int)
+
+inline class INLINE_CLASS(val a: Int)
+
+abstract class ABSTRACT_CLASS
+
+sealed class SEALED {
+    object O : SEALED()
+}

native/swift/swift-export-standalone/testData/classes/input_root/should_be_ignored_packaged.kt

@@ -0,0 +1,3 @@
+package namespace
+
+class NAMESPACED_CLASS