Fix some emoji rendering issues related to obsolete images

1) The "obsolete" images like "swimmer" need to alias to
"man_swimming" so that they can be rendered correctly.

2) There are a whole bunch of emoji-data elements
(like white_frowning_face) that have "unified" code points which
have changed to include a "terminator."

Fixes #7212

src/org/thoughtcrime/securesms/components/emoji/EmojiProvider.java

@@ -25,6 +25,7 @@ import org.thoughtcrime.securesms.components.emoji.parsing.EmojiParser;
 import org.thoughtcrime.securesms.components.emoji.parsing.EmojiTree;
 import org.thoughtcrime.securesms.util.FutureTaskListener;
 import org.thoughtcrime.securesms.util.Util;
+import org.whispersystems.libsignal.util.Pair;
 
 import java.util.concurrent.ExecutionException;
 
@@ -68,6 +69,10 @@ class EmojiProvider {
         }
       }
     }
+
+    for (Pair<String,String> obsolete : EmojiPages.OBSOLETE) {
+      emojiTree.add(obsolete.first(), emojiTree.getEmoji(obsolete.second(), 0, obsolete.second().length()));
+    }
   }
 
   @Nullable EmojiParser.CandidateList getCandidates(@Nullable CharSequence text) {

src/org/thoughtcrime/securesms/components/emoji/parsing/EmojiTree.java

@@ -32,6 +32,8 @@ public class EmojiTree {
 
   private final EmojiTreeNode root = new EmojiTreeNode();
 
+  private static final char TERMINATOR = '\ufe0f';
+
   public void add(String emojiEncoding, EmojiDrawInfo emoji) {
     EmojiTreeNode tree = root;
 
@@ -63,7 +65,13 @@ public class EmojiTree {
       tree = tree.getChild(character);
     }
 
-    return tree.isEndOfEmoji() ? Matches.EXACTLY : Matches.POSSIBLY;
+    if (tree.isEndOfEmoji()) {
+      return Matches.EXACTLY;
+    } else if (sequence.charAt(endPosition-1) != TERMINATOR && tree.hasChild(TERMINATOR) && tree.getChild(TERMINATOR).isEndOfEmoji()) {
+      return Matches.EXACTLY;
+    } else {
+      return Matches.POSSIBLY;
+    }
   }
 
   public @Nullable EmojiDrawInfo getEmoji(CharSequence unicode, int startPosition, int endPostiion) {
@@ -79,7 +87,9 @@ public class EmojiTree {
       tree = tree.getChild(character);
     }
 
-    return tree.getEmoji();
+    if      (tree.getEmoji() != null)                                                  return tree.getEmoji();
+    else if (unicode.charAt(endPostiion-1) != TERMINATOR && tree.hasChild(TERMINATOR)) return tree.getChild(TERMINATOR).getEmoji();
+    else    return null;
   }