MEDIUM: ssl: emulates the multi-cert bundles in the crtlist

MEDIUM: ssl: emulates the multi-cert bundles in the crtlist

The multi-certificates bundle was the common way of offering multiple
certificates of different types (ecdsa and rsa) for a same SSL_CTX.
This was implemented with OpenSSL 1.0.2 before the client_hello callback
was available.

Now that all versions which does not support this callback are
depracated (< 1.1.0), we can safely removes the support for the bundle
which was inconvenient and complexify too much the code.

This patch emulates the bundle loading by looking for the bundle files
when the specified file in the configuration does not exist. It then
creates new entries in the crtlist, so they will appear as new line if
they are dumped from the CLI.