KT-11588 Type aliases

Additional tests for type alias constructor & companion object:
- codegen
- error diagnostics

compiler/testData/codegen/box/typealias/typeAliasConstructor.kt

@@ -0,0 +1,5 @@
+class C(val x: String)
+
+typealias Alias = C
+
+fun box(): String = Alias("OK").x

compiler/testData/codegen/box/typealias/typeAliasObject.kt

@@ -0,0 +1,15 @@
+object OHolder {
+    val O = "O"
+}
+
+typealias OHolderAlias = OHolder
+
+class KHolder {
+    companion object {
+        val K = "K"
+    }
+}
+
+typealias KHolderAlias = KHolder
+
+fun box(): String = OHolderAlias.O + KHolderAlias.K