Reland "unpack_bootimg: Create symlink as alternate vendor ramdisk names"

Change the symlink names to
`out/vendor-ramdisk-by-name/ramdisk_${ramdisk_name}` so that they don't
name collide with other files under out/.

Bug: 184400360
Test: unpack_bootimg and check `tree out/`
Test: Forrest test avd/avd_boot_test_kernel_aosp-master
Change-Id: Id6314d102a4c43caa89f29d1cd90b1fed4b12d9a
1 file changed