[database::oracle::plugin] new mode to check blocking sessions

It should be nice to have a mode wich allows to check if there are blocking sessions on the DB

• https://www.dba-oracle.com/t_find_blocking_sessions.htm
• https://www.tutorialspoint.com/how-to-identify-blocked-and-blocking-sessions-in-oracle
• https://stackoverflow.com/questions/46886403/finding-query-from-oracle-which-is-blocking-session

see also: https://github.com/centreon/centreon-plugins/issues/4247

Here is a example of a valid SQL statement:

SQL> select l1.inst_id,l1.sid, ' IS BLOCKING ', l2.sid,l1.type,l2.type,l1.lmode,l2.lmode,l2.inst_id
 from gv$lock l1, gv$lock l2
 where l1.block =1 and l2.request > 0and l1.id1=l2.id1
 and l1.id2=l2.id2;  2    3    4

   INST_ID        SID 'ISBLOCKING'         SID TY TY      LMODE      LMODE    INST_ID
---------- ---------- ------------- ---------- -- -- ---------- ---------- ----------
         1        682  IS BLOCKING         275 TX TX          6          0          1

SQL>
SQL> SELECT blocking_session,
  sid,
  wait_class,
  seconds_in_wait
FROM v$session
WHERE blocking_session IS NOT NULL
ORDER BY blocking_session;  2    3    4    5    6    7

BLOCKING_SESSION        SID WAIT_CLASS                                                       SECONDS_IN_WAIT
---------------- ---------- ---------------------------------------------------------------- ---------------
             682        275 Application                                                                  401