[AutoCompleteTextView] Pop up menu calls `adapter.getView()`, not `adapter.getDropDownView()`

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**Description:**

When an adapter is set on an `AutoCompleteTextView`, the adapter's `getView()` method is called to get the view to show in the dropdown / popup menu. From the adapter documentation (e.g., on `ArrayAdapter`) I had expected `getDropViewView()` to be called.

**Expected behavior:**

`getDropDownView()` to be called. It is documented as:

> Gets a View that displays in the drop down popup the data at the specified position in the data set.

where as `getView()` is documented as:

> Get a View that displays the data at the specified position in the data set.

Since I'm using `AutoCompleteTextView` in an exposed **dropdown** menu (https://github.com/material-components/material-components-android/blob/master/docs/components/Menu.md#exposed-dropdown-menu-example) I expected the method with **dropdown** in the name to be called.

It's probably too late to change the code (outside of a breaking change release), but a very clear note in the documentation everywhere it demonstrates setting an adapter that `getDropDownView` is ignored would be helpful.

**Source code:**

```kotlin
val items = listOf("Item 1", "Item 2", "Item 3", "Item 4")
val adapter = object : ArrayAdapter(requireContext(), android.R.layout.simple_list_item_1, items) {
init {
setDropDownViewResource(android.R.layout.simple_list_item_2)
}

override fun getDropDownView(position: Int, convertView: View?, parent: ViewGroup): View {
// bind data to the UI here, populating the second textview in layout.simple_list_item_2
}
}
(textField.editText as? AutoCompleteTextView)?.setAdapter(adapter)
```

Instrumenting `getDropDownView` and `getView` with logging calls quickly shows that only `getView` is called.

**Android API version:** 31

**Material Library version:** 1.12.0

**Device:** Emulator

Start with docs/components/Menu.md and search the repository for AutoCompleteTextView examples that set an adapter. Verify the documented behavior against the issue's getView() and getDropDownView() observations, then add a clear note wherever relevant examples appear; done when users are told which method supplies the popup view.

Written by the indexing model from the issue text.