Add developer option to convert from FDE to FBE

This set of changes adds the screen that offers this conversion,
and the plumbing so the option is only available on suitable
devices.

It does not implement the conversion mechanism.

This is equivalent to:

https://googleplex-android-review.git.corp.google.com/#/c/805554

Change-Id: Iecc6dabd0b93c2b0c9d2fde71aa0e95d2bb66a36
diff --git a/fstab.angler b/fstab.angler
index b88cf6f..2851e14 100644
--- a/fstab.angler
+++ b/fstab.angler
@@ -5,7 +5,7 @@
 
 /dev/block/platform/soc.0/f9824900.sdhci/by-name/system       /system         ext4    ro,barrier=1                                                    wait,verify=/dev/block/platform/soc.0/f9824900.sdhci/by-name/metadata
 /dev/block/platform/soc.0/f9824900.sdhci/by-name/vendor       /vendor         ext4    ro,barrier=1                                                    wait,verify=/dev/block/platform/soc.0/f9824900.sdhci/by-name/metadata
-/dev/block/platform/soc.0/f9824900.sdhci/by-name/userdata     /data           ext4    noatime,nosuid,nodev,barrier=1,data=ordered,nomblk_io_submit,noauto_da_alloc,discard,errors=panic wait,check,forceencrypt=/dev/block/platform/soc.0/f9824900.sdhci/by-name/metadata
+/dev/block/platform/soc.0/f9824900.sdhci/by-name/userdata     /data           ext4    noatime,nosuid,nodev,barrier=1,data=ordered,nomblk_io_submit,noauto_da_alloc,discard,errors=panic wait,check,forcefdeorfbe=/dev/block/platform/soc.0/f9824900.sdhci/by-name/metadata
 /dev/block/platform/soc.0/f9824900.sdhci/by-name/cache        /cache          ext4    noatime,nosuid,nodev,barrier=1,data=ordered,nomblk_io_submit,noauto_da_alloc,errors=panic wait,check
 /dev/block/platform/soc.0/f9824900.sdhci/by-name/persist      /persist        ext4    nosuid,nodev,barrier=1,data=ordered,nodelalloc,nomblk_io_submit,errors=panic wait,notrim
 /dev/block/platform/soc.0/f9824900.sdhci/by-name/modem        /firmware       vfat    ro,shortname=lower,uid=1000,gid=1000,dmask=227,fmask=337,context=u:object_r:firmware_file:s0        wait