LibGfx+Ladybird+Userland: Don't sniff for TGA images with only raw bytes

Because TGA images don't have magic bytes as a signature to be detected,
instead assume a sequence of ReadonlyBytes is a possible TGA image only
if we are given a path so we could check the extension of the file and
see if it's a TGA image.

When we know the path of the file being loaded, we will try to first
check its extension, and only if there's no match to a known decoder,
based on simple extension lookup, then we would probe for other formats
as usual with the normal sniffing method.

Userland/Libraries/LibImageDecoderClient/Client.cpp

@@ -20,6 +20,43 @@ void Client::die()
         on_death();
 }
 
+Optional<DecodedImage> Client::decode_image_with_known_path(DeprecatedString const& path, ReadonlyBytes encoded_data)
+{
+    if (encoded_data.is_empty())
+        return {};
+
+    auto encoded_buffer_or_error = Core::AnonymousBuffer::create_with_size(encoded_data.size());
+    if (encoded_buffer_or_error.is_error()) {
+        dbgln("Could not allocate encoded buffer");
+        return {};
+    }
+    auto encoded_buffer = encoded_buffer_or_error.release_value();
+
+    memcpy(encoded_buffer.data<void>(), encoded_data.data(), encoded_data.size());
+    auto response_or_error = try_decode_image_with_known_path(path, move(encoded_buffer));
+
+    if (response_or_error.is_error()) {
+        dbgln("ImageDecoder died heroically");
+        return {};
+    }
+
+    auto& response = response_or_error.value();
+
+    if (response.bitmaps().is_empty())
+        return {};
+
+    DecodedImage image;
+    image.is_animated = response.is_animated();
+    image.loop_count = response.loop_count();
+    image.frames.resize(response.bitmaps().size());
+    for (size_t i = 0; i < image.frames.size(); ++i) {
+        auto& frame = image.frames[i];
+        frame.bitmap = response.bitmaps()[i].bitmap();
+        frame.duration = response.durations()[i];
+    }
+    return image;
+}
+
 Optional<DecodedImage> Client::decode_image(ReadonlyBytes encoded_data)
 {
     if (encoded_data.is_empty())

Userland/Libraries/LibImageDecoderClient/Client.h

@@ -31,6 +31,7 @@ class Client final
 
 public:
     Optional<DecodedImage> decode_image(ReadonlyBytes);
+    Optional<DecodedImage> decode_image_with_known_path(DeprecatedString const& path, ReadonlyBytes);
 
     Function<void()> on_death;