3.x Rename the entity base table

[WengerK]

💬 Describe the pull request

Rename base table from backerymails_sended_mail to backerymails_sent_mails

• Update existing views
• Update the entity
• Migrate data from old to new table
• Drop table when everything has been migated
• Upgrade path coverage

🗃️ Issues

This pull request is related to :

• close [Drupal - Backerymails] - Refactoring & Migrations #16
• close Table name incorrect #5

🔢 To Review

Steps to review the PR:

1. drush updatedb -y

📸 Pay attention to

• All existing data in the previous table should be migrated
• People who install the module for the 1st time should not need the updatedb, therefor nothing should break when the previous table does not exists
• The Backerymail views should be updated with the new base-table name