API PULL - Add a filter for enabling the feature

[puntope]

Changes proposed in this Pull Request:

This PR enables a filter for enabling the full Notifications feature:

If the woocommerce_gla_notifications_enabled is false

• The enable feature banner and the info in the settings page cards won't show in the UI
• wpcom_rest_api_status will return disabled -- Even setting the gla_wpcom_rest_api_status Option as approved, error or disapproved
• The Notification service won't trigger notifications (This will be done when API PULL - Validate MC connection in notifications #2336 gets merged)
• The Syncer Hooks won't schedule any notification job
• MC will sync products and coupons as usual. (old strategy)

The PR does some naming changes

NotificationsService::is_enabled() -> Just checks the filter.
Options::notifications_enabled() -> Renamed to Options::is_wpcom_api_authorized()
NotificationsService::is_ready() -> Check if NotificationsService::is_enabled() and if Options::is_wpcom_api_authorized()

Detailed test instructions:

1. Checkout this PR ( woocommerce_gla_notifications_enabled is false by default)
2. Complete the onboarding
3. Go to settings, no banner is shown
4. Set gla_wpcom_rest_api_status as approved
5. No info in GMC Card is shown
6. Set gla_wpcom_rest_api_status as error
7. No info in GMC Card is shown
8. Change some product
9. See the notification jobs are not scheduled
10. Set woocommerce_gla_notifications_enabled filter as true
11. Delete gla_wpcom_rest_api_status option
12. Banner is shown
13. Set gla_wpcom_rest_api_status as approved
14. Info is shown in the card
15. Change some product
16. See the notification jobs is scheduled

[codecov]

Codecov Report

Attention: Patch coverage is 72.22222% with 5 lines in your changes are missing coverage. Please review.

Project coverage is 62.5%. Comparing base (f19b5f7) to head (e8efb1b).
Report is 3 commits behind head on add/grant-access-to-google-wpcom-app-in-setting-page.

Additional details and impacted files

@@                                  Coverage Diff                                   @@
##             add/grant-access-to-google-wpcom-app-in-setting-page   #2340   +/-   ##
======================================================================================
  Coverage                                                    62.5%   62.5%           
- Complexity                                                   4461    4469    +8     
======================================================================================
  Files                                                         764     764           
  Lines                                                       22560   22585   +25     
  Branches                                                      543     543           
======================================================================================
+ Hits                                                        14104   14123   +19     
- Misses                                                       7999    8005    +6     
  Partials                                                      457     457           

Flag	Coverage Δ
js-unit-tests	55.3% <ø> (ø)
php-unit-tests	64.0% <72.2%> (+<0.1%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

Files	Coverage Δ
js/src/constants.js	100.0% <ø> (ø)
src/Coupon/SyncerHooks.php	74.5% <100.0%> (ø)
src/Jobs/Notifications/AbstractNotificationJob.php	100.0% <100.0%> (ø)
src/MerchantCenter/AccountService.php	96.2% <100.0%> (+<0.1%)	⬆️
src/MerchantCenter/MerchantCenterService.php	94.2% <100.0%> (+<0.1%)	⬆️
src/Product/SyncerHooks.php	83.1% <100.0%> (ø)
src/Settings/SyncerHooks.php	100.0% <100.0%> (ø)
src/Shipping/SyncerHooks.php	100.0% <100.0%> (ø)
src/Options/Options.php	62.3% <0.0%> (ø)
src/API/WP/NotificationsService.php	86.0% <0.0%> (-4.2%)	⬇️

... and 4 files with indirect coverage changes

[ianlin]

Thanks for adding the filter to enable/disable the notification service. Tested locally and it worked as expected. 👍