added def self.execute_ps_command for powershell

[IharKotau]

Issue #, if available:
AWS Support Case ID 8624255101
Description of changes:
To replace cmd command for deleting of a directory in Windows systems with Powershell command

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.

[IharKotau]

@vrr-21 @mwjones-aws I would appreciate your assistance with this PR. Thanks!

[mwjones-aws]

Hi @IharKotau . CodeDeploy agent's release process is undergoing significant changes. Because of this we are waiting to review most pull requests until we are finished updating that process, so that changes can be deployed in a reasonable time frame after they're merged.

Unfortunately I can't provide an exact date when we'll review this, but it's likely to be on the order of months.