Make PsiTypeItemTest.Inner types consistent with other tests

Renames it and removes the use of `PsiTypeItem` and psi specific
classes so that it can be moved into the common test suite.

Bug: 294556178
Test: ./gradlew
Change-Id: I4e650060048b57fa72fb7b23a203a9114a6f9b9e
diff --git a/metalava-model-psi/src/test/java/com/android/tools/metalava/model/psi/PsiTypeItemTest.kt b/metalava-model-psi/src/test/java/com/android/tools/metalava/model/psi/PsiTypeItemTest.kt
index a2232a7..eb69f8f 100644
--- a/metalava-model-psi/src/test/java/com/android/tools/metalava/model/psi/PsiTypeItemTest.kt
+++ b/metalava-model-psi/src/test/java/com/android/tools/metalava/model/psi/PsiTypeItemTest.kt
@@ -316,7 +316,7 @@
     }
 
     @Test
-    fun `Inner types`() {
+    fun `Test inner types`() {
         testJavaAndKotlin(
             java(
                 """
@@ -346,8 +346,7 @@
             // Outer<P1>.Inner<P2>
             val innerType = method.returnType()
             assertThat(innerType).isInstanceOf(ClassTypeItem::class.java)
-            assertThat((innerType as PsiTypeItem).psiType.canonicalText)
-                .isEqualTo("Outer<P1>.Inner<P2>")
+            assertThat(innerType.toCanonicalType()).isEqualTo("Outer<P1>.Inner<P2>")
             assertThat((innerType as ClassTypeItem).qualifiedName).isEqualTo("Outer.Inner")
             assertThat(innerType.parameters).hasSize(1)
             val innerTypeParameter = innerType.parameters.single()