Support stroke text style

Summary:
# Context
We are working on migrating showreel bloks ads to native implementation and one important feature is TextOverlay. In showreel bloks, the text overlay rendering heavily rely on RichTextView. We tried using TextView instead (See diff stack D63923873) but experiment shows large frame drop regressions (https://fburl.com/gdoc/fcnxfgzs) which is likely caused by the dynamic text sizing logic. To make the native implementation as close as showreel bloks, we plan to switch to RichText litho component so we can reuse similar dynamic text sizing logic from showreel bloks.

Tech spec: https://fburl.com/gdoc/myn5fzc0

# This diff
* We will need the text outline for native text overlay for 9:16 video ads in M2. This diff adds the capability of the feature. By default the effect is off. We will integrate it with the server when backend is ready.

Reviewed By: adityasharat, xzhch1622

Differential Revision: D67874677

fbshipit-source-id: 2b1eeaec66f616999a1082a4ce0ee92a6359e9fc

Author: Ale Van Praag

litho-rendercore-text/src/main/java/com/facebook/rendercore/text/TextStyle.java

@@ -71,6 +71,8 @@ public class TextStyle implements Cloneable {
   int highlightEndOffset = UNSET;
   int highlightCornerRadius = 0;
   boolean shouldLayoutEmptyText = false;
+  int strokeColor = Color.TRANSPARENT;
+  int strokeWidth = 0;
 
   boolean shouldTruncateTextUsingConstraints = false;
   int manualBaselineSpacing = Integer.MIN_VALUE;
@@ -357,4 +359,9 @@ public RoundedBackgroundProps(RectF padding, float cornerRadius, int backgroundC
       this.backgroundColor = backgroundColor;
     }
   }
+
+  public void setStrokeStyle(int strokeColor, int strokeWidth) {
+    this.strokeColor = strokeColor;
+    this.strokeWidth = strokeWidth;
+  }
 }