Allow fishing success rate to be adjustable. Adds BUKKIT-3837

By: Andre LeBlanc <andre@norcode.com>

paper-api/src/main/java/org/bukkit/entity/Fish.java

@@ -3,4 +3,26 @@ package org.bukkit.entity;
 /**
  * Represents a fishing hook.
  */
-public interface Fish extends Projectile {}
+public interface Fish extends Projectile {
+
+    /**
+     * Gets the chance of a fish biting.
+     * <p>
+     * 0.0 = No Chance.<br>
+     * 1.0 = Instant catch.
+     *
+     * @return chance the bite chance
+     */
+    public double getBiteChance();
+
+    /**
+     * Sets the chance of a fish biting.
+     * <p>
+     * 0.0 = No Chance.<br>
+     * 1.0 = Instant catch.
+     *
+     * @param chance the bite chance
+     * @throws IllegalArgumentException if the bite chance is not between 0 and 1
+     */
+    public void setBiteChance(double chance) throws IllegalArgumentException;
+}