Hi,

This patch is intended to fix bug #52792.

This uses `gnus-group-name-charset' to decode group names when
fetching from **NNTP server only**, `gnus-group-real-name` is modified
to decode group names based on their attached `charset' text property.
It is expected that when Gnus saves group names to ~/.newsrc.eld, the
text properties are correctly saved.

If we can assure only NNTP needs this special encoding, I may move the
coding coversion to nntp.el instead, and fix
`gnus-group-name-charset'.

--
LDB