AND FIL_RENAME_TABLESPACE_IN_MEM()

This is a regression from WL#7142.

The tablespace file names (fil_node_t::name) were only protected by
fil_system->mutex, but the MLOG_FILE_NAME reporting code is only holding
log_sys->mutex. So, we have to protect the file names with both
fil_system->mutex and log_sys->mutex. fil_system->mutex protection
will be needed for fil_node_open_file() and possibly other users.

fil_node_t::name: Document the mutex protection.

fil_rename_tablespace_in_mem(): Remove.

fil_rename_tablespace(): Protect fil_node_t::name by log_sys->mutex
and fil_system->mutex. Check the validity of fil_space_t::name upfront.

RB: 11014
Reviewed-by: Jimmy Yang <jimmy.yang@oracle.com>