Encryption auto detection

Note: We no longer offer encryption auto detection on XOS 11.0 and later. By default, and if supported, your device will be FBE-encrypted. This is important to protect your data and keep spying eyes out of your device, should they gain physical access to it.

How it works

1. Check if FDE encrypted
    -> if yes, dynamically set flags for FDE
    -> if no, proceed with 2.
   
2. Check if FBE encrypted
    -> if yes, dynamically set flags for FBE
    -> if no:
      -> check if /data/media exists
        -> if it does not exist, check if /data/decrypt exists:
          -> if it does, proceed with 3.
          -> if not, enable encryption
        -> if it does exist, proceed with 3.
   
3. Assume device is decrypted, remove all encryption flags
   

This means your users no longer need to flash noverity zips, force decrypt, whatever. Devices with formatted /data will be FBE-encrypted by default unless the file /data/decrypt is created before first boot.
If /data is not formatted, the ROM will automatically detect its encryption state and use that.

This implementation is a lot more tolerant and offers users easy control over encryption

Pick following commits:

https://github.com/halogenOS/android_system_core/commit/301f4659bf83063a186249742dda8e9ae44eeb00
https://github.com/halogenOS/android_system_core/commit/604da74a79aa95c43525203024da56e80ad35207
https://github.com/halogenOS/android_system_core/commit/0ff53949b0f384909727427e28ce9dd24708cee2
https://github.com/halogenOS/android_system_core/commit/e50dd23338a67d4cf9d890e93276e92bb727ac9f

Do this in your device tree:
https://github.com/halogenOS/android_device_oneplus_msm8998-common/commit/9ebd98f2d6627281f0a074d1d27e7652e2c11dde

Basically this adds autodetect_crypt and make sure you keep the FBE and FDE configs for your device, e. g. fileencryption=ice,encryptable=footer,length=-16384

Have fun