factory_install: support installing partitions from installer resources

BUG=chrome-os-partner:36725
TEST=1. Build factory install shim for two boards
     2. Make RMA shim for two boards
     3. Merge two RMA shims: ./make_image_resource.sh --force usbimg1.bin usbimg2.bin
     4. Install the merged RMA shim on two boards, check it installs the right resources
CQ-DEPEND=CL:272418
CQ-DEPEND=CL:272568
CQ-DEPEND=CL:272881
CQ-DEPEND=CL:273100

Change-Id: Id65f0e6a2b24a1132808ad222ab7502bef8dd3b7
Reviewed-on: https://chromium-review.googlesource.com/272349
Reviewed-by: Mao Huang <littlecvr@chromium.org>
Tested-by: Bowgo Tsai <bowgotsai@chromium.org>
Commit-Queue: Bowgo Tsai <bowgotsai@chromium.org>
1 file changed