Use CallableItem in place of MethodItem

The `MethodItem` type represents both a normal method as well as being
the super type of `ConstructorItem`. That organization causes a number
of issues in Metalava and has lead to quite a few issues where code
that only expected to be run on methods and not constructors was run on
both. So, a new type `CallableItem` has been added that will eventually
become the super type of both `MethodItem` and `ConstructorItem` and
`ConstructorItem` will no longer extend `MethodItem`.

This change prepares this code for that change.

Bug: 352481366
Test: ./gradlew
Change-Id: I9f2f60ce60337db55246a43e23285921a895519b
diff --git a/api/coverage/tools/ExtractFlaggedApis.kt b/api/coverage/tools/ExtractFlaggedApis.kt
index bf67187..0a3ae4f 100644
--- a/api/coverage/tools/ExtractFlaggedApis.kt
+++ b/api/coverage/tools/ExtractFlaggedApis.kt
@@ -16,9 +16,9 @@
 
 package android.platform.coverage
 
+import com.android.tools.metalava.model.CallableItem
 import com.android.tools.metalava.model.ClassItem
 import com.android.tools.metalava.model.Item
-import com.android.tools.metalava.model.MethodItem
 import com.android.tools.metalava.model.text.ApiFile
 import java.io.File
 import java.io.FileWriter
@@ -40,24 +40,24 @@
 
 fun extractFlaggedApisFromClass(
     classItem: ClassItem,
-    methods: List<MethodItem>,
+    callables: List<CallableItem>,
     packageName: String,
     builder: FlagApiMap.Builder
 ) {
-    if (methods.isEmpty()) return
+    if (callables.isEmpty()) return
     val classFlag = getClassFlag(classItem)
-    for (method in methods) {
-        val methodFlag = getFlagAnnotation(method) ?: classFlag
+    for (callable in callables) {
+        val callableFlag = getFlagAnnotation(callable) ?: classFlag
         val api =
             JavaMethod.newBuilder()
                 .setPackageName(packageName)
                 .setClassName(classItem.fullName())
-                .setMethodName(method.name())
-        for (param in method.parameters()) {
+                .setMethodName(callable.name())
+        for (param in callable.parameters()) {
             api.addParameters(param.type().toTypeString())
         }
-        if (methodFlag != null) {
-            addFlaggedApi(builder, api, methodFlag)
+        if (callableFlag != null) {
+            addFlaggedApi(builder, api, callableFlag)
         }
     }
 }