list playground submissions on game pages

[vadosnaprimer]

Meant to close #1239

The query is bad but I failed to understand adelikat's explanations on how to improve it. Select() is absolute black magic for me, and I barely ever touched db manip.

The tabs need to be sorted too, but I thought it'd be bad to sort them in the 2 foreach places, and they should be sorted on the cs side, but it crashes if I add .OrderBy(g => g.Name.Length) to my query.

Whenever we have individual PG entries we may change the listed links to point to them instead, but this should be good for now.

[Masterjun3]

Here's a query that does both sortings for you (Goals by Name Length, and inside each goal by ID descending):

PlaygroundGoals = g.Submissions
	.Where(s => s.Status == SubmissionStatus.Playground)
	.GroupBy(s => s.GameGoal)
	.OrderBy(gg => gg.Key!.DisplayName.Length)
	.Select(gg => new GoalEntry(
		gg.Key!.Id,
		gg.Key!.DisplayName,
		gg.OrderByDescending(ggs => ggs.Id)
			.Select(ggs => new SubmissionEntry(ggs.Id, ggs.Title))
			.ToList()))
	.ToList(),