feature #35519 [Mailer] Make default factories public (fabpot)
feature #35519 [Mailer] Make default factories public (fabpot)

This PR was merged into the 5.1-dev branch.

Discussion
----------

[Mailer] Make default factories public

| Q             | A
| ------------- | ---
| Branch?       | master <!-- see below -->
| Bug fix?      | no
| New feature?  | yes <!-- please update src/**/CHANGELOG.md files -->
| Deprecations? | no <!-- please update UPGRADE-*.md and src/**/CHANGELOG.md files -->
| Tickets       | Fix #35469 <!-- prefix each issue number with "Fix #", if any -->
| License       | MIT
| Doc PR        | symfony/symfony-docs#... <!-- required for new features -->

To allow registering new factories and keep the default ones available.

Commits
-------

c9863c6a6c [Mailer] Make default factories public

pierredup/symfony,curry684/symfony,ro0NL/symfony,kbond/symfony,Deamon/symfony,phramz/symfony,mpdude/symfony,xabbuh/symfony,jvasseur/symfony,bendavies/symfony,xabbuh/symfony,voronkovich/symfony,Koc/symfony,mpdude/symfony,1ed/symfony,pyrech/symfony,MatTheCat/symfony,mnapoli/symfony,jderusse/symfony,d-ph/symfony,paradajozsef/symfony,mweimerskirch/symfony,oleg-andreyev/symfony,ogizanagi/symfony,sgehrig/symfony,smatyas/symfony,mweimerskirch/symfony,symfony/symfony,mpdude/symfony,MatTheCat/symfony,oleg-andreyev/symfony,oleg-andreyev/symfony,derrabus/symfony,d-ph/symfony,Koc/symfony,garak/symfony,mnapoli/symfony,Tobion/symfony,pierredup/symfony,symfony/symfony,tgalopin/symfony,ragboyjr/symfony,Deamon/symfony,OskarStark/symfony,Slamdunk/symfony,pyrech/symfony,stof/symfony,gonzalovilaseca/symfony,lstrojny/symfony,kbond/symfony,HeahDude/symfony,kbond/symfony,bendavies/symfony,paradajozsef/symfony,tgalopin/symfony,alekitto/symfony,curry684/symfony,ogizanagi/symfony,curry684/symfony,bendavies/symfony,hhamon/symfony,Simperfit/symfony,garak/symfony,OskarStark/symfony,tgalopin/symfony,paradajozsef/symfony,garak/symfony,oleg-andreyev/symfony,voronkovich/symfony,mnapoli/symfony,jakzal/symfony,1ed/symfony,bendavies/symfony,Slamdunk/symfony,localheinz/symfony,ragboyjr/symfony,localheinz/symfony,tucksaun/symfony,smatyas/symfony,stof/symfony,smatyas/symfony,phramz/symfony,jvasseur/symfony,nicolas-grekas/symfony,chalasr/symfony,gonzalovilaseca/symfony,HeahDude/symfony,derrabus/symfony,nicolas-grekas/symfony,Tobion/symfony,ogizanagi/symfony,hhamon/symfony,jderusse/symfony,OskarStark/symfony,phramz/symfony,chalasr/symfony,hhamon/symfony,fabpot/symfony,mnapoli/symfony,HeahDude/symfony,damienalexandre/symfony,lyrixx/symfony,Deamon/symfony,curry684/symfony,Slamdunk/symfony,jakzal/symfony,smatyas/symfony,fabpot/symfony,Simperfit/symfony,garak/symfony,derrabus/symfony,alekitto/symfony,mweimerskirch/symfony,Nyholm/symfony,Simperfit/symfony,jderusse/symfony,voronkovich/symfony,Nyholm/symfony,chalasr/symfony,lyrixx/symfony,kbond/symfony,sgehrig/symfony,ragboyjr/symfony,sgehrig/symfony,ogizanagi/symfony,ro0NL/symfony,derrabus/symfony,jderusse/symfony,stof/symfony,symfony/symfony,hhamon/symfony,localheinz/symfony,xabbuh/symfony,mnapoli/symfony,chalasr/symfony,gonzalovilaseca/symfony,pyrech/symfony,Simperfit/symfony,MatTheCat/symfony,nicolas-grekas/symfony,tucksaun/symfony,d-ph/symfony,localheinz/symfony,damienalexandre/symfony,jakzal/symfony,1ed/symfony,lstrojny/symfony,ro0NL/symfony,ro0NL/symfony,stof/symfony,phramz/symfony,Slamdunk/symfony,tucksaun/symfony,jvasseur/symfony,Koc/symfony,Nyholm/symfony,lyrixx/symfony,jvasseur/symfony,lstrojny/symfony,tucksaun/symfony,Simperfit/symfony,nicolas-grekas/symfony,Deamon/symfony,OskarStark/symfony,d-ph/symfony,fabpot/symfony,pierredup/symfony,mweimerskirch/symfony,sgehrig/symfony,Koc/symfony,fabpot/symfony,alekitto/symfony,lyrixx/symfony,jakzal/symfony,Tobion/symfony,ragboyjr/symfony,pierredup/symfony,HeahDude/symfony,mpdude/symfony,tgalopin/symfony,smatyas/symfony,pyrech/symfony,paradajozsef/symfony,damienalexandre/symfony,symfony/symfony,voronkovich/symfony,damienalexandre/symfony,gonzalovilaseca/symfony,xabbuh/symfony,Nyholm/symfony,1ed/symfony,MatTheCat/symfony,Tobion/symfony,mweimerskirch/symfony,Deamon/symfony,alekitto/symfony