add CLI exclude-group filter

[rrennick]

Closes #736

This PR is an alternative to #784. #784 is a great solution if adding group exclusion were the only filter we were looking to add to the queue runners. However, we are considering adding:

• hook exclusion
• priorities
• retries
• settings screen for managing the async and cron runners

#784 works around the limitation that we cannot modify the claim_actions function definition by embedding flags in existing parameters. While that works for one flag/parameter it isn't practical for adding several. This PR avoid that by adding a new function to the base tables DB store.

It also lays the groundwork for adding additional filters. For example, excluding hooks will only require a few additional lines of code. Secondly, all added filters could be implemented on the async and cron runners through a settings screen without using similar parameter tampering.

Testing

• Disable the default runners.
• I used this hook to create test actions:

add_action( 'init', function() {
    $groups = [
      'automatewoo',
      'woocommerce',
      'woocommerce-admin',
      'internal',
    ];
    $hooks = [
      'alpha',
      'beta',
      'gamma',
      'delta',
    ];
    $group = rand( 0, 3 );
    $hook = rand( 0, 3 );
    $unique = rand( 1, 9 );

    as_schedule_single_action(
        time() + MINUTE_IN_SECONDS,
        'init_' . $hooks[ $hook ] . $unique,
        [],
        'test-' . $groups[ $group ]
    );
}, 99 );

• Allow some time for actions to be created
• Then ran the following a few minutes apart

wp action-scheduler run --group=alpha
// check that all pending past due alpha actions ran
wp action-scheduler run --exclude-group=beta
// check that beta is the only group with pending past due actions

---

Changelog

Add - Add support for excluding group(s) when using the WP CLI queue runner.

[Konamiman]

By looking at the implementation it seems that when both --group and --exclude-group are specified, only --group is taken in account. That's fine (I guess combining both is out of scope for this pr) but maybe it's something that should be explicitly stated in the help.

[rrennick]

@Konamiman Thanks for the suggestion. I've added that to the option description.