Add support for packaging modules.load.charger into vendor_[kernel_]boot

Add support for createing a modules.load.charger file in the vendor_boot
and vendor_kernel_boot images when
BOARD_VENDOR[_KERNEL_]_RAMDISK_CHARGER_MODULES_LOAD is specified.

Bug: 266752750
Change-Id: Ic8fc06566aafa5c01dff50daa6293c6cb6d0c263
Signed-off-by: Isaac J. Manjarres <isaacmanjarres@google.com>