Add support for lock expiry.

[fabianfreyer]

cc @naderman

[dvdcastro]

Unit tests are failing locally for me, please review them.

vendor/bin/phpunit local/redislock/tests/redis_lock_factory_test.php

Testing started at 3:49 PM ...
Moodle 3.9.3 (Build: 20201109), ab5949dbe283a074834710b28cf17a298c54a786
Php: 7.2.24.0.0.18.04.6, mysqli: 5.7.30-0ubuntu0.18.04.1, OS: Linux 4.15.0-101-generic x86_64
PHPUnit 7.5.20 by Sebastian Bergmann and contributors.


Failed asserting that 86400 matches expected -1.
Expected :-1
Actual   :86400
<Click to see difference>

 /vagrant/www/moodle/local/redislock/tests/redis_lock_factory_test.php:76
 /vagrant/www/moodle/lib/phpunit/classes/advanced_testcase.php:91
 

Failed asserting that a boolean is not empty.
 /vagrant/www/moodle/local/redislock/tests/redis_lock_factory_test.php:134
 /vagrant/www/moodle/lib/phpunit/classes/advanced_testcase.php:91
 

Failed asserting that a boolean is not empty.
 /vagrant/www/moodle/local/redislock/tests/redis_lock_factory_test.php:156
 /vagrant/www/moodle/lib/phpunit/classes/advanced_testcase.php:91
 

Expectation failed for method name is equal to 'setnx' when invoked at least once.
Expected invocation at least once but it never occurred.

 /vagrant/www/moodle/lib/phpunit/classes/advanced_testcase.php:91
 

Expectation failed for method name is equal to 'setnx' when invoked 1 time(s).
Method was expected to be called 1 times, actually called 0 times.

 /vagrant/www/moodle/lib/phpunit/classes/advanced_testcase.php:91
 


Time: 30.98 seconds, Memory: 128.50 MB


FAILURES!
Tests: 6, Assertions: 17, Failures: 5.

Fatal error: Uncaught coding_exception: Coding error detected, it must be fixed by a programmer: A lock was created but not released at:
/vagrant/www/moodle/local/redislock/tests/redis_lock_factory_test.php on line 74

 Code should look like:

 $factory = \core\lock\lock_config::get_lock_factory('type');
 $lock = $factory->get_lock(master372a_core_cron_test);
 $lock->release();  // Locks must ALWAYS be released like this.

 in /vagrant/www/moodle/lib/classes/lock/lock.php on line 117

Call Stack:
    0.0004     391544   1. {main}() /vagrant/www/moodle/vendor/phpunit/phpunit/phpunit:0
    0.0262    1159232   2. PHPUnit\TextUI\Command::main() /vagrant/www/moodle/vendor/phpunit/phpunit/phpunit:61
    0.0262    1159344   3. PHPUnit\TextUI\Command->run() /vagrant/www/moodle/vendor/phpunit/phpunit/src/TextUI/Command.php:162
    5.2651  130201720   4. PHPUnit\TextUI\TestRunner->doRun() /vagrant/www/moodle/vendor/phpunit/phpunit/src/TextUI/Command.php:206

coding_exception: Coding error detected, it must be fixed by a programmer: A lock was created but not released at:
/vagrant/www/moodle/local/redislock/tests/redis_lock_factory_test.php on line 74

 Code should look like:

 $factory = \core\lock\lock_config::get_lock_factory('type');
 $lock = $factory->get_lock(master372a_core_cron_test);
 $lock->release();  // Locks must ALWAYS be released like this.

 in /vagrant/www/moodle/lib/classes/lock/lock.php on line 117

Call Stack:
    0.0004     391544   1. {main}() /vagrant/www/moodle/vendor/phpunit/phpunit/phpunit:0
    0.0262    1159232   2. PHPUnit\TextUI\Command::main() /vagrant/www/moodle/vendor/phpunit/phpunit/phpunit:61
    0.0262    1159344   3. PHPUnit\TextUI\Command->run() /vagrant/www/moodle/vendor/phpunit/phpunit/src/TextUI/Command.php:162
    5.2651  130201720   4. PHPUnit\TextUI\TestRunner->doRun() /vagrant/www/moodle/vendor/phpunit/phpunit/src/TextUI/Command.php:206
   30.9895  132674296   5. core\lock\lock->__destruct() /vagrant/www/moodle/lib/classes/lock/lock.php:0

Process finished with exit code 1