Convert erofs_try_to_free_all_cached_pages() and
z_erofs_cache_release_folio().

Besides, erofs_page_is_managed() is moved to zdata.c and renamed
as erofs_folio_is_managed().
Reviewed-by: Chao Yu <chao@kernel.org>
Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>
Link: https://lore.kernel.org/r/20240305091448.1384242-6-hsiangkao@linux.alibaba.com