Taglib: Use ID3v2Tag() instead of tag() for RIFF::WAV::File

When I tried to compile VLC on my Linux system (version 6.7.3-2-cachyos), I encountered a compilation error.

Build log:

  CXX      meta_engine/libtaglib_plugin_la-taglib.lo
../../modules/meta_engine/taglib.cpp: In function ‘int ReadMeta(vlc_object_t*)’:
../../modules/meta_engine/taglib.cpp:988:17: error: cannot declare variable ‘s’ to be of abstract type ‘VlcIostream’
  988 |     VlcIostream s( p_stream );
      |                 ^
../../modules/meta_engine/taglib.cpp:186:7: note:   because the following virtual functions are pure within ‘VlcIostream’:
  186 | class VlcIostream : public IOStream
      |       ^~~~~~~~~~~
In file included from /usr/include/taglib/tfile.h:30,
                 from /usr/include/taglib/fileref.h:29,
                 from ../../modules/meta_engine/taglib.cpp:61:
/usr/include/taglib/tiostream.h:117:18: note:     ‘virtual void TagLib::IOStream::insert(const TagLib::ByteVector&, TagLib::offset_t, size_t)’
  117 |     virtual void insert(const ByteVector &data,
      |                  ^~~~~~
/usr/include/taglib/tiostream.h:127:18: note:     ‘virtual void TagLib::IOStream::removeBlock(TagLib::offset_t, size_t)’
  127 |     virtual void removeBlock(offset_t start = 0, size_t length = 0) = 0;
      |                  ^~~~~~~~~~~
../../modules/meta_engine/taglib.cpp: In function ‘int WriteMeta(vlc_object_t*)’:
../../modules/meta_engine/taglib.cpp:1395:44: error: invalid conversion from ‘TagLib::Tag*’ to ‘TagLib::ID3v2::Tag*’ [-fpermissive]
 1395 |             WriteMetaToId3v2( riff_wav->tag(), p_item );
      |                               ~~~~~~~~~~~~~^~
      |                                            |
      |                                            TagLib::Tag*
../../modules/meta_engine/taglib.cpp:1119:43: note:   initializing argument 1 of ‘void WriteMetaToId3v2(TagLib::ID3v2::Tag*, input_item_t*)’
 1119 | static void WriteMetaToId3v2( ID3v2::Tag* tag, input_item_t* p_item )
      |                               ~~~~~~~~~~~~^~~
../../modules/meta_engine/taglib.cpp: In instantiation of ‘TagLib::File* VLCTagLib::ExtResolver<T>::createFileFromStream(TagLib::IOStream*, bool, TagLib::AudioProperties::ReadStyle) const [with T = TagLib::MPEG::File]’:
../../modules/meta_engine/taglib.cpp:151:7:   required from here
../../modules/meta_engine/taglib.cpp:161:20: warning: ‘TagLib::MPEG::File::File(TagLib::IOStream*, TagLib::ID3v2::FrameFactory*, bool, TagLib::AudioProperties::ReadStyle)’ is deprecated [-Wdeprecated-declarations]
  161 |             return new T(s, ID3v2::FrameFactory::instance(), false, AudioProperties::Fast);
      |                    ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
In file included from ../../modules/meta_engine/taglib.cpp:74:
/usr/include/taglib/mpegfile.h:140:7: note: declared here
  140 |       File(IOStream *stream, ID3v2::FrameFactory *frameFactory,
      |       ^~~~

It's a bit puzzling because I haven't faced this error before, but I made some necessary fixes in the code to get things working.

WriteMetaToId3v2 expects a TagLib::ID3v2::Tag instead of TagLib::Tag, hence replaced the usage of the tag() method with ID3v2Tag() when working with RIFF::WAV::File.

https://github.com/taglib/taglib/blob/master/taglib/riff/wav/wavfile.h#L124

Additionally, to resolve the compilation error, the function signatures of insert and removeBlock have been adjusted to align with the base class functions.

https://github.com/taglib/taglib/blob/920d97606b258aba18c336f3b85b544a05383a1c/taglib/toolkit/tiostream.h#L117