vm-repair 0.2.3: Enable custom vm username for linux repair VM, add more validators

[swbae31]

Ready for merge after signoff

Changes:

1. Enable custom vm username for Linux repair VMs
2. Rename scenario tests to better match doc format
3. Add vm password and username validators for fast fails when user provides bad input
4. fix Typos
5. Run command will return with status SUCCESS even when the script itself fails. However the script status will return with ERROR.
6. Hide long running messages when --verbose
7. Return script_status in return json for repair run command

[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/$EXT "git+https://github.com/swbae31/azure-cli-extensions.git@version0.2.3#subdirectory=src/$EXT&egg=$EXT"

[yonzhan]

@zikalino will help review.

[swbae31]

@zikalino @yonzhan any updates on this?