[datadog_monitor] Add enable_samples monitor options

[liashenko]

Recently we added samples for ci-tests and ci-pipeline monitors, which users can enable using enable_samples attribute.

Adding enable_samples to monitor options spec and docs.

[phillip-dd]

This will need to pull in the updated go client auto generated from the spec PR. Then we'll also need to set the value similar to

terraform-provider-datadog/datadog/resource_datadog_monitor.go

Lines 627 to 631 in efa529e

	if attr, ok := d.GetOk("enable_logs_sample"); ok {
	o.SetEnableLogsSample(attr.(bool))
	} else {
	o.SetEnableLogsSample(false)
	}

[rtrieu]

Looks good!

[phillip-dd]

@rtrieu please don't merge this, it isn't functional yet. Please wait for a member of the @DataDog/integrations-tools-and-libraries to approve.