[5.3] Fixes for redis queue driver

[halaei]

Changes

• Implement migrateExpiredJobs() using eval instead of watch-multi-exec (check and set) transactions to prevent issue Redis queue driver may never pop delayed jobs if the push rate is high #12653.
• Increment attempts counter when reserving job, instead of when releasing it, so that fatal errors be considered as tries.
• Migrate expired delayed jobs but not expired release ones when expire is null. Issue RedisQueue::pop() will never pop delayed jobs when expire is null #12595
• A few transaction guards for the times we moving jobs between main/reserved and delayed queues, so that the jobs are not lost in Redis server in the case of network/client failures.

Upgrade guides required

The changes require Redis >= 2.6.0. I don't think it will be an issue, since 2.6.0 itself is too old! Also, Redis eval command should not be disabled in the Redis configuration file, which I don't think is a big deal - why should somebody do that.

[taylorotwell]

Can you explain what the $reserved parameter passed to the constructor is for?

[halaei]

$reserved is the json serialization of the reserved job. The string is not the same as the original job anymore. It is computed inside the LUA script and we can't expect PHP to be able to compute that using json_encode() in the exact way. The exact value of the $reserved string is required for delete and release operations.