Adding feature to export snapshots instead of images.

[bebattis]

This allows for non-generalized (or non-sysprepped) osStates to be copied and deployed across regions. Will work as approved work around for copying VMs across regions which need to maintain identical runtimes.

---

Spoke with @tamirkamara on this previously offline. I was able to get the extension configured locally with the Azdev tools and ran a quick test to replicate a single region. This was successful. As far as development best practices, there may be a better way to do this, but for now I've essentially added two if/else statements and the switch parameter --export-as-snapshot which will 1) skip the image creation, and 2) place the temp snapshots into the target_resource_group vs the transient_resource-group depending on what the desired output is.

LMK if there is anything else that needs testing or improvement. Feel free to reach out again directly.

[azuresdkci]

If this PR is for a new extension or change to an existing extension, use the following to try out the changes in this PR:

docker run -it microsoft/azure-cli:latest
export EXT=<NAME>
pip install --upgrade --target ~/.azure/cliextensions/$EXT "git+https://github.com/bebattis/azure-cli-extensions.git@copy-snapshot-feature#subdirectory=src/$EXT&egg=$EXT"

[bebattis]

EDIT: Needed to add this line to the create_target.py

Not too sure on this error... should I un-comment "pylint: disable=too-many-statements" ?