LibGfx/TIFF: Also seek after reading the last tag

The `read_tag()` function is not mandated to keep the reading head at a
meaningful position, so we also need to align the pointer after the last
tag. This solves a bug where reading the last field of an IFD, which is
placed after the tags, was incorrect.

Userland/Libraries/LibGfx/ImageFormats/TIFFLoader.cpp

@@ -498,14 +498,14 @@ class TIFFLoadingContext {
  auto next_tag_offset = TRY(m_stream->tell());
 
  for (u16 i = 0; i < number_of_field; ++i) {
- TRY(m_stream->seek(next_tag_offset));
  if (auto maybe_error = read_tag(); maybe_error.is_error() && TIFF_DEBUG)
  dbgln("Unable to decode tag {}/{}", i + 1, number_of_field);
 
  // Section 2: TIFF Structure
  // IFD Entry
  // Size of tag(u16) + type(u16) + count(u32) + value_or_offset(u32) = 12
  next_tag_offset += 12;
+ TRY(m_stream->seek(next_tag_offset));
  }
 
  TRY(read_next_idf_offset());