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

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

@@ -0,0 +1,32 @@
+#nullable disable
+using System.Text.Json;
+
+namespace NadekoBot.Modules.Nsfw.Common;
+
+public sealed class SankakuImageDownloader : ImageDownloader<SankakuImageObject>
+{
+    private readonly string _baseUrl;
+
+    public SankakuImageDownloader(HttpClient http)
+        : base(Booru.Sankaku, http)
+    {
+        _baseUrl = "https://capi-v2.sankakucomplex.com";
+        _http.AddFakeHeaders();
+    }
+
+    public override async Task<List<SankakuImageObject>> DownloadImagesAsync(
+        string[] tags,
+        int page,
+        bool isExplicit = false,
+        CancellationToken cancel = default)
+    {
+        // explicit probably not supported
+        var tagString = ImageDownloaderHelper.GetTagString(tags);
+
+        var uri = $"{_baseUrl}/posts?tags={tagString}&limit=50";
+        var data = await _http.GetStringAsync(uri);
+        return JsonSerializer.Deserialize<SankakuImageObject[]>(data, _serializerOptions)
+                             .Where(x => !string.IsNullOrWhiteSpace(x.FileUrl) && x.FileType.StartsWith("image"))
+                             .ToList();
+    }
+}