crypto: add .free() and .reset() methods to reduce memory leaks with -autofree (#16992)

* Fix unsafe pointer

I was compile vab with '-prod' and it was needed  to fix and it is of course warning

* Add files via upload

* reduce memory  leak s sha512

* add method .free() and .reset() for some

vlib/crypto/rc4/rc4.v

@@ -20,6 +20,15 @@ mut:
 	j u8
 }
 
+// free the resources taken by the Cipher `c`
+[unsafe]
+pub fn (mut c Cipher) free() {
+	$if prealloc {
+		return
+	}
+	unsafe { c.s.free() }
+}
+
 // new_cipher creates and returns a new Cipher. The key argument should be the
 // RC4 key, at least 1 byte and at most 256 bytes.
 pub fn new_cipher(key []u8) !Cipher {