[CI][Archery][Dev] Add missing headers to email reports

[kou]

Describe the enhancement requested

See also: https://lists.apache.org/thread/xwtzbqxkyx5q44xnyvpgzd02vnfqovr3

We're using email_* in https://github.com/apache/arrow/tree/main/dev/archery/archery/templates for nightly email reports that are sent to builds@arrow.apache.org: https://lists.apache.org/list.html?builds@arrow.apache.org

They have only From:/To:/Subject:. We should add the following headers:

• MIME-Version: 1.0
• Content-Type: text/plain; charset="utf-8"
• Message-Id: ${AUTO_GENERATED_MESSAGE_ID}
• Date: ${DATE_IN_RFC_2822}

Component(s)

Developer Tools, Continuous Integration, Archery