Update testing to use Pester and create a `sensu-go` asset

[derekgroh]

Pull Request Checklist

General

• [X] Update Changelog following the conventions laid out on Our CHANGELOG Guidelines

• [X] Update README with any necessary configuration snippets

• [X] Binstubs are created if needed

• [X] RuboCop passes

• [X] Existing tests pass

Purpose

• Favor using Windows Native testing Pester for windows plugins.
• Updates repository for Bonsai usage.

Known Compatibility Issues

None

[derekgroh]

Scripts need to be in the bin directory to have SensuGo source them properly.

[majormoses]

I see, can you please call that out clearly in the changelog so that people understand why it's happening and what they need to do. We need to communicate changes clearly especially when they are breaking. Someone could still be installing Ruby and the gem outside of the context of an asset and it likely would still work as it used to. Additionally there are likely still sensu-ruby users out there relying on it's old behavior. It does not matter if you break one or all users, breaking is breaking.

Example:

### Breaking Changes
- moved all powershell scripts directly into the bin directory, you will need to update your check definition paths to reflect. This change is required to create an asset that works with sensu-go. `@derekgroh`