PHPLIB-293 Add support for a comment parameter to the aggregate command

[kvwalker]

https://jira.mongodb.org/browse/PHPLIB-293

[jmikola]

Please add the comment option to both the PHP docs preceding the Aggregate class and the RST documentation when you get a chance.

Rather than copy the text from Find operation's comment option, I'd suggest using the description in the 3.6 manual:

Users can specify an arbitrary string to help trace the operation through the database profiler, currentOp, and logs.

[jmikola]

Since comment and maxTimeMS are the same in the sense that we want to check if they're isset() and then copy them as-is into the $cmd document, I propose creating a foreach as we have in other command helpers:

foreach (['comment', 'maxTimeMS'] as $option) {
    if (isset($this->options[$option])) {
        $cmd[$option] = $this->options[$option];
    }
}

allowDiskUse is always set, so we can leave its earlier assignment as-is.

[kvwalker]

I added the comment option to the RST documentation, but what are the PHP docs preceding the Aggregate class?

[jmikola]

what are the PHP docs preceding the Aggregate class?

I was referring to the doc block before class Aggregate:

mongo-php-library/src/Operation/Aggregate.php

Line 57 in 7508380

* Supported options:

Sorry if that was unclear.

[jmikola]

Good catch! I just came across #423 while looking through closed PRs and was going to pop in to ask about this, but you beat me to it 👍

[jmikola]

Good to squash and merge