Creating SMTP provider

[eladkal]

Body

Currently we have send_email as util function and EmailOperator as part of core.
I think email/smtp is tightly coupled to core for historical reasons but we can decouple it without making a breaking change.

The task:
Investigate/Implement the option of creating smtp provider

Committer

• I acknowledge that I am a maintainer/committer of the Apache Airflow project.