Fix autocomplete spacing bug (Input Screen) (#6487)

Task/Issue URL:
https://app.asana.com/1/137249556945/project/488551667048375/task/1210916405340681?focus=true

### Description

- Removes the top margin and ensures the autocomplete list scrolls
beneath the shadow of the Input Field.

### Steps to test this PR

- [x] Scroll the autocomplete on the Input Screen
- [x] Verify that the list scrolls under the Input Field + shadow

Author: joshliebe

duckchat/duckchat-impl/src/main/res/layout/fragment_input_screen.xml

@@ -26,6 +26,7 @@
         android:layout_width="0dp"
         android:layout_height="wrap_content"
         android:layout_marginTop="@dimen/keyline_2"
+        android:elevation="1dp"
         app:layout_constraintEnd_toEndOf="parent"
         app:layout_constraintStart_toStartOf="parent"
         app:layout_constraintTop_toTopOf="parent" />
@@ -34,7 +35,6 @@
         android:id="@+id/viewPager"
         android:layout_width="0dp"
         android:layout_height="0dp"
-        android:layout_marginTop="@dimen/keyline_3"
         android:clipToPadding="false"
         app:layout_constraintBottom_toBottomOf="parent"
         app:layout_constraintEnd_toEndOf="parent"

duckchat/duckchat-impl/src/main/res/layout/fragment_search_tab.xml

@@ -50,7 +50,7 @@
         android:layout_height="match_parent"
         android:background="?attr/daxColorBrowserOverlay"
         android:clipToPadding="false"
-        android:elevation="4dp"
+        android:paddingTop="@dimen/keyline_3"
         android:paddingBottom="64dp"
         tools:itemCount="3"
         tools:listitem="@layout/item_autocomplete_search_suggestion"