fix(output): ensure that vulnerabilities are sorted by ID across groups in table output

[G-Rath]

While prototyping some changes to help with #1567, I discovered that the table output format is not explicitly sorting vulnerabilities across their groups, meaning we're assumingly using the order that the API gives us, and means our current output does not actually follow a predictable order.

To address this, I've modified the table outputter to sort vulnerability groups by the first ID in each group as a group by definition will always have at least one ID and the first ID should be the one primary one since we already sort ids within each group as part of building the general results

[G-Rath]

note that this is actually modifying the value of pkg.Groups on the struct, which applies outside of this function - I actually thought Go didn't work like this, but apparently it does.

I have somewhat mixed feelings about doing it, as generally this is considered bad practice (especially as it's not obvious), but it saves us a few lines of code + a variable, and any bug that it causes I would expect to be because whatever is being impacted should itself be doing a sort if it cares about the order...

[hogo6002]

I think the best approach here is probably to replace everything with Output/Result, which is already sorted and contains all the data we need to display (even extras). I should probably update it for consistency (since container scanning result uses Output/Result).

[G-Rath]

I've had an initial go at this over in #1609 which seemed promising but still has some work to go, so I'd like to land this PR in the short-term if that's ok as it greatly reduces the noise in some of the other work I'm doing with the test suite

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 69.32%. Comparing base (c100a26) to head (f710b63).
Report is 5 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1598      +/-   ##
==========================================
+ Coverage   69.30%   69.32%   +0.02%     
==========================================
  Files         200      200              
  Lines       19033    19036       +3     
==========================================
+ Hits        13190    13196       +6     
+ Misses       5135     5133       -2     
+ Partials      708      707       -1     

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