test: Rename test directories to use an explicit order

For convenience, rename the directories so the order is explicit in the name.
Make the simple test run first, to save time if it's not working.

test/t-01-simple_local/msmtprc

@@ -0,0 +1,21 @@
+account default
+
+host testserver
+port 1025
+
+tls on
+tls_trust_file config/domains/testserver/cert.pem
+
+from user@testserver
+
+auth on
+user user@testserver
+password secretpassword
+
+account baduser : default
+user unknownuser@testserver
+password secretpassword
+
+account badpasswd : default
+user user@testserver
+password badsecretpassword