Move goldfish local image methods to a new file

This commit moves methods from goldfish_local_image_local_instance to a
new file. Their functionalities are not changed. Remote host goldfish
will use the methods to process images.

Test: acloud-dev create -vv --local-instance --local-image \
      --local-system-image --local-boot-image
Test: acloud-dev create -vv --local-instance --local-image \
      --local-system-image \
      out/target/product/generic_x86_64/system.img \
      --local-boot-image \
      out/target/product/generic_x86_64/boot-5.10.img \
      --avd-type goldfish
Bug: 185094559
Change-Id: I069a0388f38b0b6653bf3306ae5745cd26ccd4a8
10 files changed