Add new filter ep_skip_autosave_sync and enable autosave sync for protected_content feature

[rebeccahum]

Description of the Change

Problem: When a user has the protected_content feature enabled, and they work on a draft but they never hit "Save draft" and instead, rely on the WordPress autosave, it won't show up in the Draft post listing screen (/wp-admin/edit.php?post_status=draft&post_type=post):

This is because it never gets synced, as we disable it here:

ElasticPress/includes/classes/Indexable/Post/SyncManager.php

Lines 284 to 289 in aaf2a33

	if ( defined( 'DOING_AUTOSAVE' ) && DOING_AUTOSAVE ) {
	// Bypass saving if doing autosave
	// @codeCoverageIgnoreStart
	return;
	// @codeCoverageIgnoreEnd
	}

This PR does two things:

• Introduces the ep_skip_autosave_sync filter
• Returns false for the aforementioned filter when the protected_content feature is enabled

Alternate Designs

I'm not sure if it would be beneficial to pass in the __FUNCTION__ for the second parameter during apply_filters() if one wanted to customize disabling the autosave sync on function-basis, since we have action_set_object_terms, action_sync_on_update, etc. to make it more granular:

		if ( apply_filters( 'ep_disable_autosave_sync', true, __FUNCTION__ ) ) {
			if ( defined( 'DOING_AUTOSAVE' ) && DOING_AUTOSAVE ) {
				// Bypass saving if doing autosave
				// @codeCoverageIgnoreStart
				return;
				// @codeCoverageIgnoreEnd
			}
		}

Curious on your thoughts @felipeelia for that.

Possible Drawbacks

N/A.

Verification Process

1. Enable the protected_content feature
2. Start drafting a new post and wait for WordPress to autosave
3. Go to the Draft post listing screen at /wp-admin/edit.php?post_status=draft&post_type=post and expect to see the autosaved draft

Checklist:

• I have read the CONTRIBUTING document.
• My code follows the code style of this project.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have added tests to cover my change.
• All new and existing tests passed.

Changelog Entry

Fixed: autosaved drafts not showing up in draft post listing when using protected_content

Credits

Props @rebeccahum

[felipeelia]

Hey @rebeccahum, I'm finally getting to this one. I like the idea of adding __FUNCTION__ as a parameter so people can opt out of some scenarios, can you please add that too?

In addition to that, do you think it'd be possible to add some tests? End-to-end tests checking if that works as expected and also does not affect published posts is what I have in mind. Thanks!

[rebeccahum]

@felipeelia Done and done!

[rebeccahum]

@felipeelia Thanks for the feedback, I think I got it working now!