feat: add gif speed up and speed down command

src/main/kotlin/cn/rtast/fancybot/util/misc/GIF.kt

@@ -12,7 +12,7 @@ import com.madgag.gif.fmsware.GifDecoder
 import java.awt.image.BufferedImage
 import java.io.ByteArrayOutputStream
 
-fun GifDecoder.makeGif(frames: List<BufferedImage>): ByteArray {
+fun GifDecoder.makeGif(frames: List<BufferedImage>, speed: Float? = null): ByteArray {
     val estimatedSize = frames.size * 50 * 1024
     val byteArrayOutputStream = ByteArrayOutputStream(estimatedSize)
     val encoder = AnimatedGifEncoder()
@@ -20,7 +20,13 @@ fun GifDecoder.makeGif(frames: List<BufferedImage>): ByteArray {
     encoder.setRepeat(0)
     val delays = frames.indices.map { this.getDelay(this.frameCount - it - 1) }
     frames.indices.forEach { i ->
-        encoder.setDelay(delays[i])
+        if (speed == null) {
+            encoder.setDelay(delays[i])
+        } else {
+            var delay = this.getDelay(i)
+            delay = (delay / speed).toInt()
+            encoder.setDelay(delay.coerceAtLeast(1))
+        }
         encoder.addFrame(frames[i])
     }
     encoder.finish()