Extend cmdlet Get-IshPublicationOutput to return PublicationOutputs that use/contain a specific content object

[ddemeyer]

Up to v0.14 Get-IshPublicationOutput returns you PublicationOutput information based on its metadata (identifiers). What if this cmdlet returns you PublicationOutuputs based on content objects that it is using.

Important to note is that given languages, resolutions and usage of ´ishconditions`, variables, and DITA constructs like conref/keyref/... it is impossible to give an accurate view. What can be done is give a best effort super-set filter on PublicationOutputs that are very likely to use the given content object. For example it can still be that the given image is only used in a different resolution, or is not part of the conref or was conditionally filtered out.

• Parameter -IshObject currently only accepts IshPublicationOutputs; if it would accepts IshModule or IshImage then that could be the starting point for a PublicationOutput25.Containing
• Extend Pester tests

PublicationOutput25.Containing will only use the LogicalId and exact version of the incoming IshObject (IshModule, etc) so language and resolution and conditions and more will be ignored.