Add RunCode command for CodeLens providers

[TylerLeonhardt]

PR Summary

This feature adds a generic PowerShell.RunCode command so that CodeLens providers have a mechanism for executing whatever code is needed in the codelens...

An example:
Invoke-Build could offer a Run task | Debug task CodeLens:

This would call PowerShell.RunCode so that it can run:

script: Invoke-Build
args: TaskName, path/to/foo.build.ps1

With this, Invoke-Build, psake, or any other big name module could provide CodeLens without having to ship their own extension or add to PSES directly. They can take advantage of public types already available within the PSES session and use RunCode to run their specific scenario.

PR Checklist

Note: Tick the boxes below that apply to this pull request by putting an x between the square brackets.
Please mark anything not applicable to this PR NA.

• PR has a meaningful title
• Summarized changes
• PR has tests
• This PR is ready to merge and is not work in progress
  • If the PR is work in progress, please add the prefix WIP: to the beginning of the title and remove the prefix when the PR is ready

[TylerLeonhardt]

I have the 2 classes needed for Invoke-Build to work:
https://gist.github.com/TylerLeonhardt/0d5147ad409c1b90a22fe18d87070097

these would just need to be Add-Type'd and then you call:

$psEditor.Components.Get([Microsoft.PowerShell.EditorServices.CodeLenses.ICodeLenses]).Providers.Add([PSakeCodeLensProvider]::new())

(ignore the references to PSake - I started with it but then changed to InvokeBuild later... consider them... the same :) )

[TylerLeonhardt]

example module - https://github.com/TylerLeonhardt/InvokeBuildCodeLens

[TylerLeonhardt]

Ok I did some refactoring and added a test - this should be good now :)

[TylerLeonhardt]

I'm not going to bother backporting this