Fixed some crashes in response strings source generator, reorganized more submodules into their folders

src/NadekoBot/Modules/Searches/_Common/LowerCaseNamingPolicy.cs

@@ -0,0 +1,12 @@
+#nullable disable
+using System.Text.Json;
+
+namespace SystemTextJsonSamples;
+
+public class LowerCaseNamingPolicy : JsonNamingPolicy
+{
+    public static LowerCaseNamingPolicy Default = new();
+
+    public override string ConvertName(string name)
+        => name.ToLower();
+}