Allow ConvertTo-Xml to emit CLIXML (the same XML format as Export-Clixml)

[mklement0]

Summary of the new feature/enhancement

Follow-up from #8308 (comment), quoting @SteveL-MSFT:

Ideally, it seems like we should have had ConvertTo-Xml take a -Format parameter that supported CliXml and other xml formats rather than having this confusion between ExportTo-CliXml and ConvertTo-Xml having incompatible xml formats.

Note that the documentation is lacking, as of this writing, as it mistakenly suggests that ConvertTo-Xml is the in-memory equivalent of Export-CliXml - see MicrosoftDocs/PowerShell-Docs#3310

Update: Adding dedicated ConvertTo-CliXml and ConvertFrom-CliXml cmdlets has been requested and green-lit (#3898), though the associated PR has gone stale: #5815

In light of that, it may be better to leave ConvertTo-Xml alone and simply fix / amend its documentation.

[SteveL-MSFT]

Marking as First-Time-Issue as I think this should be relatively straight forward to add a parameter and have it use some of the internal APIs used by Export-CliXml to do the conversion.

[ece-jacob-scott]

Hack Illinois participant
Working with @rjmholt and @TylerLeonhardt

I will take this one on.