Prepare bundle for ODM 2.0

[alcaeus]

• Drop PHP < 7.2
• Require development versions of ODM 2.0 (will change as we move into alpha and beta stages)
• Drop YAML driver
• Update configuration to instantiate new connection classes
• Make service repositories compatible with GridFS repositories
• Use PHPUnit 7.3
• Update data collectors for ext-mongodb (needs
  Replace QueryLogger in tests with CommandLogger mongodb-odm#1866)
• Update query logger for ext-mongodb

[alcaeus]

Query logging and profiling is now taken care of. The pretty option for the profiler is now useless and will most likely be dropped. Since we're now logging all commands, any output we show there may simply be run using db.runCommand(...). I don't think it's worth implementing a lot of logic to convert a find command to the corresponding db.query.find() call for the console. Even if, we may as well make that the default behaviour and show raw command documents next to their pretty console equivalents - both options make the option completely obsolete.

The changes in this PR showed me that I forgot a few additional options that need to be deprecated, so we'll most likely have another minor release (3.6) containing the last few deprecations. This would also serve as a last PHP 5 compatible release that would be supported along ODM 1.3.

[malarzm]

Didn't go through tests but src changes look good 👍

[malarzm]

According to ctor this can be nullable

[alcaeus]

Ah, good catch. Thanks!