Added "Warning" icon instead of "CW" text. (#1138)

* Added «Warning» icon instead of «CW» text.
Icon source: https://ionicons.com/

* Updated icon to "sms_failed"

app/src/main/java/com/keylesspalace/tusky/ComposeActivity.java

@@ -29,6 +29,7 @@ import android.content.res.Resources;
 import android.graphics.Bitmap;
 import android.graphics.PorterDuff;
 import android.graphics.drawable.Drawable;
+import android.media.Image;
 import android.net.Uri;
 import android.os.AsyncTask;
 import android.os.Build;
@@ -202,7 +203,7 @@ public final class ComposeActivity
     private TootButton tootButton;
     private ImageButton pickButton;
     private ImageButton visibilityButton;
-    private Button contentWarningButton;
+    private ImageButton contentWarningButton;
     private ImageButton emojiButton;
     private ImageButton hideMediaToggle;
 
@@ -1484,12 +1485,10 @@ public final class ComposeActivity
         if (show) {
             statusMarkSensitive = true;
             contentWarningBar.setVisibility(View.VISIBLE);
-            contentWarningButton.setTextColor(ContextCompat.getColor(this, R.color.tusky_blue));
             contentWarningEditor.setSelection(contentWarningEditor.getText().length());
             contentWarningEditor.requestFocus();
         } else {
             contentWarningBar.setVisibility(View.GONE);
-            contentWarningButton.setTextColor(ThemeUtils.getColor(this, android.R.attr.textColorTertiary));
         }
         updateHideMediaToggle();
 

app/src/main/res/drawable/ic_cw_24dp.xml

@@ -0,0 +1,9 @@
+<vector xmlns:android="http://schemas.android.com/apk/res/android"
+    android:width="24dp"
+    android:height="24dp"
+    android:viewportWidth="24"
+    android:viewportHeight="24">
+  <path
+      android:fillColor="#FF000000"
+      android:pathData="M20,2L4,2c-1.1,0 -1.99,0.9 -1.99,2L2,22l4,-4h14c1.1,0 2,-0.9 2,-2L22,4c0,-1.1 -0.9,-2 -2,-2zM13,14h-2v-2h2v2zM13,10h-2L11,6h2v4z"/>
+</vector>

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

@@ -242,17 +242,16 @@
             android:visibility="gone"
             tools:src="@drawable/ic_eye_24dp" />
 
-        <androidx.appcompat.widget.AppCompatButton
+        <ImageButton
             android:id="@+id/composeContentWarningButton"
             style="?attr/image_button_style"
             android:layout_width="36dp"
             android:layout_height="36dp"
             android:layout_marginEnd="4dp"
-            android:background="?attr/selectableItemBackgroundBorderless"
             android:contentDescription="@string/action_content_warning"
             android:padding="4dp"
-            android:text="@string/text_content_warning_button"
-            android:tooltipText="@string/action_content_warning" />
+            android:tooltipText="@string/action_content_warning"
+            app:srcCompat="@drawable/ic_cw_24dp"/>
 
         <ImageButton
             android:id="@+id/composeEmojiButton"