[fenix] For https://github.com/mozilla-mobile/fenix/issues/11004: Fix invisible text on migration UI

For some text and colors, we were using the default styling where
possible. These styles contain references that react to theme changes
like dark mode. Since the migration UI does not respect these changes,
we should not use them.

app/src/main/java/org/mozilla/fenix/migration/MigrationProgressActivity.kt

@@ -94,7 +94,7 @@ class MigrationProgressActivity : AbstractMigrationProgressActivity() {
             text = getString(R.string.migration_update_app_button, getString(R.string.app_name))
             setTextColor(ContextCompat.getColor(context, R.color.white_color))
         }
-        migration_button.setBackgroundResource(R.drawable.button_background)
+        migration_button.setBackgroundResource(R.drawable.migration_button_background)
         migration_button_progress_bar.visibility = View.INVISIBLE
         // Keep the results list up-to-date.
         statusAdapter.submitList(results.toItemList())

app/src/main/res/drawable/migration_button_background.xml

@@ -0,0 +1,9 @@
+<?xml version="1.0" encoding="utf-8"?>
+<!-- This Source Code Form is subject to the terms of the Mozilla Public
+   - License, v. 2.0. If a copy of the MPL was not distributed with this
+   - file, You can obtain one at http://mozilla.org/MPL/2.0/. -->
+
+<shape xmlns:android="http://schemas.android.com/apk/res/android">
+    <corners android:radius="4dp"/>
+    <solid android:color="#312A65" />
+</shape>

app/src/main/res/layout/activity_migration.xml

@@ -66,7 +66,8 @@
                 android:layout_marginRight="@dimen/migration_margin_horizontal_large"
                 android:lineHeight="24sp"
                 android:text="@string/migration_description"
-                android:textAppearance="@style/Body16TextStyle"
+                android:textColor="@color/primary_text_light_theme"
+                android:textAppearance="@style/TextAppearance.MaterialComponents.Body1"
                 app:layout_constraintBottom_toTopOf="@+id/migration_status_list"
                 app:layout_constraintLeft_toLeftOf="parent"
                 app:layout_constraintRight_toRightOf="parent"
@@ -121,7 +122,7 @@
             android:background="@android:color/transparent"
             android:text="@string/migration_updating_app_button_text"
             android:textSize="@dimen/migration_button_text_size"
-            android:textAppearance="@style/NeutralButton"
+            android:textAppearance="@style/Widget.MaterialComponents.Button.TextButton"
             tools:text="Updating Firefox…" />
 
     </LinearLayout>

app/src/main/res/layout/migration_list_item.xml

@@ -26,7 +26,8 @@
             android:layout_height="wrap_content"
             android:layout_marginStart="24dp"
             android:layout_marginEnd="32dp"
-            android:textAppearance="@style/Body16TextStyle"
+            android:textColor="@color/primary_text_light_theme"
+            android:textAppearance="@style/TextAppearance.MaterialComponents.Body1"
             app:layout_constraintBottom_toBottomOf="parent"
             app:layout_constraintEnd_toEndOf="parent"
             app:layout_constraintStart_toEndOf="@+id/migration_status_image"