MDEV-24408 Crash-safe DROP DATABASE

Description of how DROP DATABASE works after this patch

- Collect list of tables
- DDL log tables as they are dropped
- DDL log drop database
- Delete db.opt
- Delete data directory
- Log either DROP TABLE or DROP DATABASE to binary log
- De active ddl log entry

This is in line of how things where before (minus ddl logging) except that
we delete db.opt file last to not loose it if DROP DATABASE fails.

On recovery we have to ensure that all dropped tables are logged in
binary log and that they are properly dropped (as with atomic drop
table).
No new tables be dropped as part of recovery.

Recovery of active drop database ddl log entry:

- If drop database was logged to ddl log but was not found in the binary
  log:
  - drop the db.opt file and database directory.
  - Log DROP DATABASE to binary log
- If drop database was not logged to ddl log
  - Update binary log with DROP TABLE of the dropped tables. If table list
    is longer than max_allowed_packet, then the query will be split into
    multiple DROP TABLE/VIEW queries.

Other things:
- Added DDL_LOG_STATE and 'current database' as arguments to
  mysql_rm_table_no_locks(). This was needed to be able to combine
  ddl logging of DROP DATABASE and DROP TABLE and make the generated
  DROP TABLE statements shorter.
- To make the DROP TABLE statement created by ddl log shorter, I changed
  the binlogged query to use current directory and omit the directory
  part for all tables in the current directory.
- Merged some DROP TABLE and DROP VIEW code in ddl logger.  This was done
  to be able get separate DROP VIEW and DROP TABLE statements in the binary
  log.
- Added a 'recovery_state' variable to remember the state of dropped
  tables and views.
- Moved out code that drops database objects (stored procedures) from
  mysql_rm_db_internal() to drop_database_objects() for better code reuse.
- Made mysql_rm_db_internal() global so that could be used by the ddl
  recovery code.

sql/sql_table.h

@@ -37,6 +37,7 @@ typedef struct st_key KEY;
 typedef struct st_key_cache KEY_CACHE;
 typedef struct st_lock_param_type ALTER_PARTITION_PARAM_TYPE;
 typedef struct st_order ORDER;
+typedef struct st_ddl_log_state DDL_LOG_STATE;
 
 enum enum_explain_filename_mode
 {
@@ -177,7 +178,10 @@ bool mysql_checksum_table(THD* thd, TABLE_LIST* table_list,
 bool mysql_rm_table(THD *thd,TABLE_LIST *tables, bool if_exists,
                     bool drop_temporary, bool drop_sequence,
                     bool dont_log_query);
-int mysql_rm_table_no_locks(THD *thd, TABLE_LIST *tables, bool if_exists,
+int mysql_rm_table_no_locks(THD *thd, TABLE_LIST *tables,
+                            const LEX_CSTRING *db,
+                            DDL_LOG_STATE *ddl_log_state,
+                            bool if_exists,
                             bool drop_temporary, bool drop_view,
                             bool drop_sequence,
                             bool dont_log_query, bool dont_free_locks);