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

src/NadekoBot/Modules/Nsfw/_Common/Downloaders/DerpibooruImageDownloader.cs

@@ -0,0 +1,33 @@
+#nullable disable
+using System.Net.Http.Json;
+
+namespace NadekoBot.Modules.Nsfw.Common;
+
+public class DerpibooruImageDownloader : ImageDownloader<DerpiImageObject>
+{
+    public DerpibooruImageDownloader(HttpClient http)
+        : base(Booru.Derpibooru, http)
+    {
+    }
+
+    public override async Task<List<DerpiImageObject>> DownloadImagesAsync(
+        string[] tags,
+        int page,
+        bool isExplicit = false,
+        CancellationToken cancel = default)
+    {
+        var tagString = ImageDownloaderHelper.GetTagString(tags, isExplicit);
+        var uri =
+            $"https://www.derpibooru.org/api/v1/json/search/images?q={tagString.Replace('+', ',')}&per_page=49&page={page}";
+        using var req = new HttpRequestMessage(HttpMethod.Get, uri);
+        req.Headers.AddFakeHeaders();
+        using var res = await _http.SendAsync(req, cancel);
+        res.EnsureSuccessStatusCode();
+
+        var container = await res.Content.ReadFromJsonAsync<DerpiContainer>(_serializerOptions, cancel);
+        if (container?.Images is null)
+            return new();
+
+        return container.Images.Where(x => !string.IsNullOrWhiteSpace(x.ViewUrl)).ToList();
+    }
+}