first_stage_init: add support to skip module load failures

Extend androidboot.first_stage_console cmdline property to enable
skipping module load failures without stopping at a serial console. This
is useful for GKI development.

Set androidboot.first_stage_console=2 for this behavior.

Bug: 155296582
Test: verify behavior for values 0, 1, and 2
Change-Id: I068c631a22c848e45a421b297b1acae1b3deb3c1