test: Move tests from emacs to emacs-show

This requires changing the contents of the crypto tests, as one thread
that was marked read by the earlier tests in test/emacs is no longer
marked read.

This moves tests for:

- 09d19ac "test: emacs: toggle eliding of non-matching messages in
   `notmuch-show'", which should have actually read: "test: emacs:
   toggle processing of cryptographic MIME parts in `notmuch-show'".
   See commit 19ec74c5.

- 5ea1dbe "test: emacs: toggle eliding of non-matching messages in
  `notmuch-show'"

- 345faab "test: emacs: toggle thread content indentation in
  `notmuch-show'"

Signed-off-by: Ethan Glasser-Camp <ethan@betacantrips.com>