Convert spam letters to a LocalizedDataset (#36393)

* Convert spam letters to a LocalizedDataset

* Error -> warning

* Comments

* Add migrations for old spam mail entities

Content.Shared/Paper/RandomPaperContentComponent.cs

@@ -0,0 +1,17 @@
+using Content.Shared.Dataset;
+using Robust.Shared.Prototypes;
+
+namespace Content.Shared.Paper;
+
+/// <summary>
+/// If added to an entity that has a <see cref="PaperComponent"/>, the name,
+/// description and contents of the paper will be replaced with a random
+/// entry from the specified <see cref="LocalizedDatasetPrototype"/>.
+/// Requires <see cref="PaperComponent"/>.
+/// </summary>
+[RegisterComponent]
+public sealed partial class RandomPaperContentComponent : Component
+{
+    [DataField(required: true)]
+    public ProtoId<LocalizedDatasetPrototype> Dataset;
+}