Feature: Support filtering custom emoji in reaction view (#836)

* Support filtering custom emojis in reaction keyboard.

* Move creation of EditText to conditional block.

* Clear unused comment

* Update requests variable when publishing filter results so the images displayed will be correct.

* Combine text fields in emoji reaction keyboard, create new initializer for EmojiCategory so it can be copied properly.

* Performance optimization and fixed a typo in filter.

* improve layout

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Co-authored-by: sk <sk22@mailbox.org>

mastodon/src/main/java/org/joinmastodon/android/model/EmojiCategory.java

@@ -1,5 +1,6 @@
 package org.joinmastodon.android.model;
 
+import java.util.ArrayList;
 import java.util.List;
 
 public class EmojiCategory{
@@ -10,4 +11,8 @@ public class EmojiCategory{
 		this.title=title;
 		this.emojis=emojis;
 	}
+	public EmojiCategory(EmojiCategory category){
+		this.title = category.title;
+		this.emojis = new ArrayList<>(category.emojis);
+	}
 }