feat: support gif reverse and fix get image bug

src/main/kotlin/cn/rtast/fancybot/util/str/Base64.kt

@@ -0,0 +1,22 @@
+/*
+ * Copyright © 2024 RTAkland
+ * Author: RTAkland
+ * Date: 2024/9/8
+ */
+
+
+package cn.rtast.fancybot.util.str
+
+import java.util.*
+
+fun String.encodeToBase64(): String {
+    return Base64.getEncoder().encodeToString(this.toByteArray())
+}
+
+fun ByteArray.encodeToBase64(): String {
+    return Base64.getEncoder().encodeToString(this)
+}
+
+fun String.decodeToString(): String {
+    return String(Base64.getDecoder().decode(this))
+}