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/Applications/ImageViewer/ViewWidget.cpp

@@ -168,7 +168,7 @@ void ViewWidget::load_from_file(DeprecatedString const& path)
     // Spawn a new ImageDecoder service process and connect to it.
     auto client = ImageDecoderClient::Client::try_create().release_value_but_fixme_should_propagate_errors();
 
-    auto decoded_image_or_error = client->decode_image(mapped_file.bytes());
+    auto decoded_image_or_error = client->decode_image_with_known_path(path, mapped_file.bytes());
     if (!decoded_image_or_error.has_value()) {
         show_error();
         return;