Emails: Logic to show either inbox selector or domains picker or domains CTA buy #6648463

Changes proposed in this Pull Request

This pull request adds the logic to show in upgrade->emails mailboxes if we have mailboxes to show. It will show either add a domain CTA or select domain if we have available ones.

Testing instructions

Have the following sites ready:
Site with no domains, site with one domain and no email subscription, sites with more than one domain with email subscriptions, and a site with mailboxes configured

Test 1, Site with no domains:

1. Go to the url: /inbox/{your-site-slug-with-no-domains}
2. Check that the inbox management screen is presenting you with a CTA to buy a domain

Test 2, site with one domain and no email subscription

1. Go to the url: /inbox/{your-site-slug-with-domain-and-no-email}
2. Check that the inbox management screen is presenting you with email comparison page

Test 3, have a site with several domains without subscriptions

1. Go to the url: /inbox/{your-site-with-several-domains-and-no-emails}
2. Check that the inbox management screen is presenting you with a domain selector, that takes you to email comparison page.

Test 4, have a site with minimum a domain with subscriptions

1. Go to the url: /inbox/{your-site-with-at-least-a-domain-and-emails}
2. Check that the inbox management screen is presenting you with a placeholder screen, this screen will be developed shortly.

Regression Test

The component EmailListInactive has been “upgraded” to change it’s wording when it is being used in the mailbox component. Also, the component EmailsHome has been updated to do not show active domains (domains with subscriptions) when it is presented from inbox management screen. We need to check that the component EmailsHome keeps working as it was doing it before:

BEFORE	AFTER

Related to {1200182182542585-as-1200879615791996}