refactor to mautrix 0.17.x; update deps

vendor/maunium.net/go/mautrix/crypto/goolm/cipher/main.go

@@ -0,0 +1,17 @@
+// cipher provides the methods and structs to do encryptions for olm/megolm.
+package cipher
+
+// Cipher defines a valid cipher.
+type Cipher interface {
+	// Encrypt encrypts the plaintext.
+	Encrypt(key, plaintext []byte) (ciphertext []byte, err error)
+
+	// Decrypt decrypts the ciphertext.
+	Decrypt(key, ciphertext []byte) (plaintext []byte, err error)
+
+	//MAC returns the MAC of the message calculated with the key.
+	MAC(key, message []byte) ([]byte, error)
+
+	//Verify checks the MAC of the message calculated with the key against the givenMAC.
+	Verify(key, message, givenMAC []byte) (bool, error)
+}