added config for newsletter in frontend

[torhoehn]

Description

Until now there wasn't a config field to hide newsletter elements from frontend. I orientated at the wishlist module, because for wishlist it was already possible.

Manual testing scenarios

1. Open Backend
2. Go to Stores -> Configuration -> Customers -> Newsletter
3. Set 'Enabled' to 'No'
4. Newsletter will be hidden from footer, customer registration, customer account and customer account sidebar

Contribution checklist

• Pull request has a meaningful description of its purpose
• All commits are accompanied by meaningful commit messages
• All new or changed code is covered with unit/integration tests (if applicable)
• All automated tests passed successfully (all builds on Travis CI are green)

[larsroettig]

Hi @torhoehn,
for your contribution currently the unit tests are failed can you fix this this ?

best regards,

Lars

[torhoehn]

@larsroettig The functional test could not start correctly I think, but the rest looks fine for me now.

[larsroettig]

@torhoehnI restarted the test if it is done I will check again

[magento-engcom-team]

Hi @larsroettig, thank you for the review.
ENGCOM-3134 has been created to process this Pull Request

[sidolov]

Hi @torhoehn , we found one more scenario that should be covered in scope of the provided changes:

Steps:

1. Create User 'John'
2. Disable Newsletter Subscription
3. Login as John
4. Navigate to /newsletter/manage/ directly on the browser

Expected:
404 - Page not found

Actual:
Newsletter Subscription page opens

[torhoehn]

@sidolov I‘ll implement this later this month.

[sidolov]

Hi @torhoehn , will you continue progress with PR?

[torhoehn]

@sidolov Yes, I'm just back from vacation.

[sivaschenko]

Hi @torhoehn , are you going to continue the progress with this PR?

[torhoehn]

@sivaschenko Yes, I'm just a little stuck with the unit test.

[sivaschenko]

@torhoehn great! Feel free to contact me in slack if you need any help with the unit tests

[sivaschenko]

Thanks for collaboration! Can you please fix the code styles to comply with PSRs and be consistent with the codebase

[magento-engcom-team]

Hi @sivaschenko, thank you for the review.
ENGCOM-3134 has been created to process this Pull Request

[torhoehn]

@magento-engcom-team What kind of response is needed here?

[sivaschenko]

Hi @torhoehn sorry, looks like I forgot to remove the "needs update" label.

[ghost]

Hi @torhoehn, thank you for your contribution!
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[magento-engcom-team]

Hi @torhoehn. Thank you for your contribution.
We will aim to release these changes as part of 2.3.1.
Please check the release notes for final confirmation.