Change "appendQuotedText" to "useSmartReply" in Rfc822Output

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
1 file changed