Port SRP tests to the new test framework

Also add negative tests for password mismatch.

Reviewed-by: Richard Levitte <levitte@openssl.org>

test/README.ssltest.md

diff --git a/test/README.ssltest.md b/test/README.ssltest.md
index 3d0fe91..a326967 100644
--- a/test/README.ssltest.md
+++ b/test/README.ssltest.md
@@ -179,6 +179,9 @@
   protocols can be specified as a comma-separated list, and a callback with the
   recommended behaviour will be installed automatically.
 
+* SRPUser, SRPPassword - SRP settings. For client, this is the SRP user to
+  connect as; for server, this is a known SRP user.
+
 ### Default server and client configurations
 
 The default server certificate and CA files are added to the configurations