Add toolbox_ramdisk

Intended to be installed in the generic ramdisk.
This may be executed in init_first_stage where there is no dynamic
linker, so it must be -static linked.

Bug: 383081955
Test: Presubmit
Test: Verify kernel modules are loaded in klog
Change-Id: I1b4e25970c35e6c0cce8be0edeab909e18ae46ba