Modify masterbar module to include new unified admin color schemes file

[getdave]

Alternative to #17750.

As discussed in p1604929101083300-slack-ajax this PR repurposes and extends the existing Masterbar module to become a more all purpose module for any customizations required to the WPAdmin Dashboard experience on WP.com.

Specifically, where there was previously only the A8C_WPCOM_Masterbar class, we now add an additional A8C_WPCOM_Unified_Admin_Color_Schemes class and init that from the main file as well.

In the future, other classes could be added.

Please note that @obenland has already started work on customising the masterbar module here so we could look to land that. However, as it stands my PR (ie: this one) contains less code and is more "bare bones" and thus might be easier to merge.

Changes proposed in this Pull Request:

• Add A8C_WPCOM_Unified_Admin_Color_Schemes class to masterbar module and init from main file.
• Repurpose master bar module to become an all-purpose module for any customizations required to the WPAdmin Dashboard experience on WP.com.
• Add PHP namespace to the module.
• Move individual concerns into separate directories (eg: /masterbar, /unified-admin-color-schemes...etc).

Jetpack product discussion

• paYJgx-17t-p2#comment-1391
• p1604929101083300-slack-ajax

Does this pull request change what data or activity we track or use?

No

Testing instructions:

• Checkout PR
• Modify init method of modules/masterbar/unified-admin-color-schemes.php to include some debug output.
• Check that debug output is shown only on admin pages.
• Verify existing masterbar works as previously.

Proposed changelog entry for your changes:

• Repurpose master bar module to become an all-purpose module for any customizations required to the WPAdmin Dashboard experience on WP.com.
• Add unified color schemes class to masterbar module and init from main file.
• Add PHP namespace to the module.
• Move individual concerns into separate directories (eg: /masterbar, /unified-admin-color-schemes...etc).

[jetpackbot]

Scheduled Jetpack release: December 1, 2020.
Scheduled code freeze: November 23, 2020

E2E results is available here (for debugging purposes): https://jetpack-e2e-dashboard.herokuapp.com/pr-17762

Thank you for the great PR description!

When this PR is ready for review, please apply the [Status] Needs Review label. If you are an a11n, please have someone from your team review the code if possible. The Jetpack team will also review this PR and merge it to be included in the next Jetpack release.

Generated by 🚫 dangerJS against 6a4090d

[getdave]

I've just noticed that @obenland has already started work on customising the masterbar module here so we could look to land that. However, as it stands my PR (ie: this one) contains less code and is more "bare bones" and thus might be easier to merge.

[marekhrabe]

This works well for me and the testing echo I've done in the color scheme class has worked in wp-admin correctly ✅

I think we are missing one last step and that is updating the module definition in modules/module-headings.php, since the name and description were updated. yarn build should get you sorted and you should commit the updated file.

[marekhrabe]

I've rested everything again with a code confirmed to be run in the color schemes class. With remaining issues externalized, I think we should be good proceeding and have a base for other color scheme tasks.

[getdave]

FYI anyone who comes to this and wonders what happened to syncing this code via Fusion please see

p1605115584001400-slack-ajax-reports

we can sync the code later if we need to (it's currently not synced by fusion)

[getdave]

Thanks for merging @obenland. I really appreciate that.