feat: add gravatar command

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

@@ -9,6 +9,7 @@ package cn.rtast.fancybot.util.str
 
 import java.awt.Graphics2D
 import java.net.URLEncoder
+import java.security.MessageDigest
 
 fun setTruncate(origin: String, g2d: Graphics2D, maxWidth: Int = 500): String {
     val fontMetrics = g2d.fontMetrics
@@ -50,4 +51,14 @@ fun Int.formatToMinutes(): String {
 
 val String.proxy get() = this.replace("https://", "https://proxy.rtast.cn/https/")
 
-val String.uriEncode get() = URLEncoder.encode(this, "UTF-8")
+val String.uriEncode get() = URLEncoder.encode(this, "UTF-8")
+
+fun String.getMD5(): String {
+    return this.toByteArray().getMD5()
+}
+
+fun ByteArray.getMD5(): String {
+    val md = MessageDigest.getInstance("MD5")
+    val hashBytes = md.digest(this)
+    return hashBytes.joinToString("") { "%02x".format(it) }
+}