cryptfs: Add Adiantum support

Adiantum is a crypto method Android is supporting for devices
which don't have AES CPU instructions.  See the paper
"Adiantum: length-preserving encryption for entry-level processors"
(https://eprint.iacr.org/2018/720.pdf) for more details.

We add Adiantum to our list of supported crypto types.

Bug: 112010205
Test: Tested on a device
Change-Id: Ic190a9b90fc8bc077fdc7d60c9d5ae8d8f555025

cryptfs.cpp

@@ -316,6 +316,10 @@ constexpr CryptoType default_crypto_type = CryptoType()
 
 constexpr CryptoType supported_crypto_types[] = {
     default_crypto_type,
+    CryptoType()
+        .set_property_name("adiantum")
+        .set_crypto_name("xchacha12,aes-adiantum-plain64")
+        .set_keysize(32),
     // Add new CryptoTypes here.  Order is not important.
 };