When replying or fowarding an HTML message, we now send both plain text and
HTML bodies as a multi-part mime message. We take special care to ensure the
message bodies are in their own multi-part block and do not interfere with
any additional attachments to the message.
bug 3060920
Backport-Of: I2fc3cb4e1f65bcc28486a62731b44b0ee0a99719
Change-Id: I89ec2795b55ceb7472a8ee3db2dc8f50cf537d9c
Slight API change to make it more clear what the method parameter is for.
Also add some additonal test conditions to the Rfc822Output tests.
Reapply changes in CL https://android-git.corp.google.com/g/#change,99090
Change-Id: I7a48c9544e48cbdf44b14f4b1f8d92fe01f7861e
Todd Kennedy