PHPLIB-879: Convert command monitoring tests to unified format

[jmikola]

https://jira.mongodb.org/browse/PHPLIB-879

POC for mongodb/specifications#1221. Commit message will be updated after that PR is merged.

[jmikola]

Two test failures are related to this discussion I opened on the specs PR:

1) MongoDB\Tests\UnifiedSpecTests\UnifiedSpecTest::testCommandMonitoring with data set "command-monitoring/commands: A successful command with a non-primary read preference" (MongoDB\Tests\UnifiedSpecTests\UnifiedTestCase Object (...))
Unsupported keys: readPreference
Failed asserting that an array is empty.

2) MongoDB\Tests\UnifiedSpecTests\UnifiedSpecTest::testCommandMonitoring with data set "command-monitoring/find: A successful find with options" (MongoDB\Tests\UnifiedSpecTests\UnifiedTestCase Object (...))
Unsupported keys: readPreference
Failed asserting that an array is empty.