Merge changes from topic "fastboot_fetch"

* changes:
  fuzzy_fastboot: Add tests for fetch:vendor_boot
  fuzzy_fastboot: Add conformance test for getvar:max-fetch-size.
  fastboot driver: repack vendor boot ramdisk
  fastboot driver: Allow colon in partition name when flashing
  fastboot driver: add fetch command in driver
  fastboot driver: RunAndReadBuffer don't allocate too much mem
  fastboot driver: add RunAndReadBuffer helper
  fastboot driver: Fix ownership of fd in fastboot_buffer.
  fastboot driver: fix message
  fastbootd: add O_CLOEXEC/O_BINARY for OpenPartition
  fastbootd: add read arg to OpenPartition
  fastbootd: Add fetch command on device
  fastbootd: Add getvar max-fetch-size.