Unifying multiple all-apps implementations

> Using a single layout for the all-apps content
> Removing some unnecessary themes
> Fixing search chashes in SecondaryDisplayLauncher

Bug: 259733681
Test: Existing TAPL tests verify that Launcher/AllApps work properly
Change-Id: Icd5310316499cd421bc039cdbd4d398b813cd477

quickstep/src/com/android/launcher3/taskbar/allapps/TaskbarAllAppsContainerView.java

@@ -17,6 +17,7 @@ package com.android.launcher3.taskbar.allapps;
 
 import android.content.Context;
 import android.util.AttributeSet;
+import android.view.View;
 import android.view.WindowInsets;
 
 import com.android.launcher3.DeviceProfile;
@@ -42,6 +43,19 @@ public class TaskbarAllAppsContainerView extends
         return super.onApplyWindowInsets(insets);
     }
 
+    @Override
+    protected View inflateSearchBox() {
+        // Remove top padding of header, since we do not have any search
+        mHeader.setPadding(mHeader.getPaddingLeft(), 0,
+                mHeader.getPaddingRight(), mHeader.getPaddingBottom());
+
+        TaskbarAllAppsFallbackSearchContainer searchView =
+                new TaskbarAllAppsFallbackSearchContainer(getContext(), null);
+        searchView.setId(R.id.search_container_all_apps);
+        searchView.setVisibility(GONE);
+        return searchView;
+    }
+
     @Override
     protected boolean isSearchSupported() {
         return false;
@@ -53,4 +67,10 @@ public class TaskbarAllAppsContainerView extends
         // TODO(b/240670050): Remove this and add header protection for the taskbar entrypoint.
         mBottomSheetBackground.setBackgroundResource(R.drawable.bg_rounded_corner_bottom_sheet);
     }
+
+    @Override
+    public boolean isInAllApps() {
+        // All apps is always open
+        return true;
+    }
 }