Don't support removing an email when creating another

Remove the `id` param from FolderSupport.Create::create_email_async.
Fix up all implementations and call sites. Update App.DraftManager to
explicitly handle removing the old draft after creating the new one.

This ensures the custom folder delete support gets used and in
particular, ensures that old drafts under Gmail disappear ASAP.

Fixes #76
5 jobs for wip/76-gmail-drafts in 16 minutes and 13 seconds (queued for 1 second)
Status Job ID Name Coverage
  Build
failed #390997
fedora

00:03:39

passed #390998
ubuntu

00:16:12

 
  Test
skipped #390999
flatpak
 
  Deploy
skipped #391000
review
skipped #391001
allowed to fail manual
stop_review
 
Name Stage Failure
failed
fedora Build
 Problem: conflicting requests
- nothing provides pkgconfig(telepathy-glib) >= 0.19.9 needed by folks-devel-1:0.13.1-2.fc31.i686
- nothing provides pkgconfig(telepathy-glib) >= 0.19.9 needed by folks-devel-1:0.13.1-2.fc31.x86_64
(try to add '--skip-broken' to skip uninstallable packages)
Uploading artifacts...
WARNING: build/meson-logs/meson-log.txt: no matching files
WARNING: build/meson-logs/testlog.txt: no matching files
ERROR: No files to upload
ERROR: Job failed: exit code 1