fs_config: add bin paths of flattened apexes

Added missing partitions (/product and /vendor).

APEXes can be put in /system, /system_ext, /product, and /vendor.
Binaries within "flattened" apexes should be marked as executable.

Bug: 167383491
Bug: 169025459
Test: OVERRIDE_TARGET_FLATTEN_APEX=true m vendorimage with a vendor apex
      simg2img $OUT/vendor.img vendor.img
      debugfs -R 'ls -l /vendor/apex/com.android.foo/bin' vendor.img
      => check if binaries are executable
Change-Id: I67284166d70c98a2a184b47e7052ade8b9039df9