Opportunity to choose e-mail identity / alias as "From" when sending an email

As requested on the last community meeting here is the port of this topic, copied from TJC. There are several threads regarding that topic - https://together.jolla.com/question/165583/opportunity-to-choose-e-mail-identity-alias-as-from-when-editing-email/

There are some people missing the opportunity to choose an alias as “from” when sending an email.
It was discussed on this community meeting - https://irclogs.sailfishos.org/logs/%23sailfishos-meeting/%23sailfishos-meeting.2020-11-12.log.html

This isn’t something that we currently have in the pipeline, but it’s useful functionality and we’ll look further into how this could be integrated into the UI. It would be good to have the topic moved from TJC to Sailfish OS Forum and we’d welcome your ideas about how it could work there.

In Windows Mobile when answering an email the receiving alias was automatically preset as sender when you replied.

#info additional ways to contrib: investigate the QMF framework’s ability to handle aliases (if missing, implementation is just as heartly welcome)
#info We can question also if we want to put this at QMF level. Maybe the right level can be in nemo-qml-plugin-email, because it’s just aliases in account. I think QMF is better, but it should be well thought in advance before running to code.

Here’s a link to nemo-qml-plugin-email in case anyone wants to dig there: https://git.sailfishos.org/mer-core/nemo-qml-plugin-email

And QMF: https://git.sailfishos.org/mer-core/messagingframework
And this is where the header is built : https://git.sailfishos.org/mer-core/nemo-qml-plugin-email/blob/master/src/emailmessage.cpp#L253