Support bootconfig in first stage init and fs_mgr

Androidboot parameters are being moved from the kernel commandline to
bootconfig.
fs_mgr looks for these parameters in properties and falls back to
reading directly from /proc/cmdline. So both of these sources are
updated for bootconfig.
The androidboot parameters from /proc/bootconfig
are added as ro.boot properties, and fs_mgr will fall back to searching
/proc/bootconfig if it is too early.

Test: boot cuttlefish with androidboot.fstab_suffix and
androidboot.hardware in bootconfig and not in cmdline.
Test: atest CtsFsMgrTestCases
Bug: 173815685

Change-Id: Iea36a0da94c26e1aa37d97c576725e0ad77cd3ad