update outpack metadata

[M-Kusumgar]

This just updates the metadata data classes to more closely resemble the outpack json schema. You can go on the link to the schema and compare with the kotlin data classes. I am actually not sure where this is tested. I don't think this actually is as far as I can tell which is fair enough as this is just the data class definitions

This update was required because you would get the error below if you tried to look at the summary of the packet that was run with a detached head (so not on any branch and so the git.branch would be null in the metadata) and the frontend would receive this error:

{
    "error": {
        "detail": "Error while extracting response for type [packit.model.OutpackResponse<packit.model.PacketMetadata>] and content type [application/json]",
        "error": "OTHER_ERROR"
    },
    "data": {},
    "status": "failure"
}

i don't think i can test the case when we have git.branch as null because that requires me to do a detached checkout in packit which sounds messy, we will know pretty quickly if this works to solve the error if we deploy to packit.dide.ic.ac.uk and the error goes away

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 96.00%. Comparing base (ced309d) to head (8c58616).

Additional details and impacted files

@@           Coverage Diff           @@
##             main      #96   +/-   ##
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  Coverage   96.00%   96.00%           
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  Files         106      106           
  Lines         975      975           
  Branches      252      252           
=======================================
  Hits          936      936           
  Misses         38       38           
  Partials        1        1           

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