[FIR] Expand aliased type before checking for exposure

compiler/fir/analysis-tests/testData/resolve/visibility/exposedTypeAlias.kt

@@ -11,4 +11,8 @@ class C {
 }
 
 typealias <!EXPOSED_TYPEALIAS_EXPANDED_TYPE!>AInner0<!> = A.Inner
-typealias BInner0 = B.Inner
+typealias BInner0 = B.Inner
+
+private typealias MyString = String
+
+fun foo(): MyString = ""

compiler/fir/analysis-tests/testData/resolve/visibility/exposedTypeAlias.txt

@@ -37,3 +37,7 @@ FILE: exposedTypeAlias.kt
     }
     public final typealias AInner0 = R|A.Inner|
     public final typealias BInner0 = R|B.Inner|
+    private final typealias MyString = R|kotlin/String|
+    public final fun foo(): R|MyString| {
+        ^foo String()
+    }