ALTER TABLE…ALGORITHM=INPLACE is unnecessarily refused due to innodb_force_recovery

The function ha_innobase::check_if_supported_inplace_alter() refuses ALGORITHM=INPLACE operation if innodb_force_recovery has been specified. This is unnecessarily strict; only the values 4,5,6 will effectively corrupt the database and require any writes to be blocked. In MariaDB 10.2 we have the flag high_level_read_only that should be used instead.

Furthermore, the high_level_read_only flag should be set if newraw was specified for the InnoDB system tablespace.

I noticed this during the MDEV-13134 code review.