erofs: adapt managed inode operations into folios

This patch gets rid of erofs_try_to_free_cached_page() and fold it
into .release_folio().

It also moves managed inode operations into zdata.c, which simplifies
the code a bit.  No logic changes.

Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>
Reviewed-by: Yue Hu <huyue2@coolpad.com>
Link: https://lore.kernel.org/r/20230526201459.128169-5-hsiangkao@linux.alibaba.com