Start a 10.0.x branch to use the Symfony Mailer module as the default emailing system with Varbase 10.0.x

Problem/Motivation

📌 Switch from the deprecated Swift Mailer module replaced by Symfony Mailer Fixed
📌 Remove the Mail System module. To switch to Symfony Mailer Back-compatibility only on the Varbase 10.0.x branch Fixed
#3251531: Start a 9.1.x branch for Varbase and Varbase Project to support Bootstrap 5 →

Proposed resolution

• Have a full switch to Symfony Mailer under the 9.1.x branch
• Set the Symfony Mailer as the default emailing system under the Varbase 9.1.x branch

Remaining tasks

• ✅ File an issue about this project
• ✅ Addition/Change/Update/Fix to this project
• ✅ Testing to ensure no regression
• ➖ Automated unit/functional testing coverage
• ➖ Developer Documentation support on feature change/addition
• ➖ User Guide Documentation support on feature change/addition
• ✅ Code review from 1 Varbase core team member
• ✅ Full testing and approval
• ✅ Credit contributors
• ✅ Review with the product owner
• ✅ Update Release Notes and Update Helper on new feature change/addition
• ✅ Release varbase-10.0.0-alpha1 → , varbase_email-9.1.0-alpha1

Varbase update type:

• ➖ No Update
• ➖ Optional Update
• ✅ Forced Update
• ➖ Forced Update if Unchanged

User interface changes

• N/A

API changes

• N/A

Data model changes

• Issue #3266671 → : Started a 10.0.x branch to use the Symfony Mailer module as the default emailing system with Varbase 10.0.x