game timer: Add chess-style buffer time option (#10598)

* UI Changes

* Add new buffer time options

* Main functionality

* Final implementation

Also added player UI for when they are using their buffer time (timer turns green)

Mage/src/main/java/mage/constants/MatchBufferTime.java

@@ -0,0 +1,41 @@
+package mage.constants;
+
+/**
+ * The time a player receives whenever the timer starts. This ticks down before their normal time,
+ * and refreshes to full every time the timer starts, creating a sort of buffer. Similar to how to
+ * chess clocks work.
+ * 
+ * Based off of MatchTimeLimit
+ *
+ * @author alexander-novo
+ */
+public enum MatchBufferTime {
+    NONE(0, "None"),
+    SEC__05(5, "5 Seconds"),
+    SEC__10(10, "10 Seconds"),
+    SEC__15(15, "15 Seconds"),
+    SEC__20(20, "20 Seconds"),
+    SEC__25(25, "25 Seconds"),
+    SEC__30(30, "30 Seconds");
+
+    private final int matchSeconds;
+    private final String name;
+
+    MatchBufferTime(int matchSeconds, String name) {
+        this.matchSeconds = matchSeconds;
+        this.name = name;
+    }
+
+    public int getBufferTime() {
+        return matchSeconds;
+    }
+
+    public String getName() {
+        return name;
+    }
+
+    @Override
+    public String toString() {
+        return name;
+    }
+}