feat(pki): add ssh_pki_ctx to ssh_session

The session struct now contains an ssh_pki_ctx struct as its member to allow for passing user configured pki options across many functions.
The ssh_options_set API has been extended to allow users to set this member.

Signed-off-by: Praneeth Sarode <praneethsarode@gmail.com>
Reviewed-by: Jakub Jelen <jjelen@redhat.com>
Reviewed-by: Eshan Kelkar <eshankelkar@galorithm.com>

include/libssh/libssh.h

@@ -421,6 +421,7 @@ enum ssh_options_e {
     SSH_OPTIONS_CERTIFICATE,
     SSH_OPTIONS_PROXYJUMP,
     SSH_OPTIONS_PROXYJUMP_CB_LIST_APPEND,
+    SSH_OPTIONS_PKI_CONTEXT,
 };
 
 enum {

include/libssh/session.h

@@ -288,6 +288,10 @@ struct ssh_session_struct {
     /* counters */
     ssh_counter socket_counter;
     ssh_counter raw_counter;
+
+    /* PKI context structure containing various parameters to configure PKI
+     * operations */
+    struct ssh_pki_ctx_struct *pki_context;
 };
 
 /** @internal