at_c: atclient_notify should check if atclient_notify_params argument is complete

[JeremyTubongbanua]

atclient_atkey atkey;
atclient_atkey_init(&atkey);
atclient_notify_params notify_params;
atclient_notify_params_init(&notify_params);
if ((exit_code = atclient_utils_find_atserver_address(ATSERVER_HOST, ATSERVER_PORT, ATSIGN, &atserver_host, &atserver_port)) != 0)
{
    goto exit;
}
if ((exit_code = atclient_utils_populate_atkeys_from_homedir(&atkeys, ATSIGN)) != 0)
{
    goto exit;
}
if ((exit_code = atclient_pkam_authenticate(&atclient1, atserver_host, atserver_port, &atkeys, ATSIGN)) != 0)
{
    goto exit;
}
/*
 * 1a. Set up atkey in our notify_params struct
 */
if((exit_code = atclient_notify_params_set_atkey(&notify_params, &atkey)) != 0) {
    goto exit;
}
/*
 * 1b. Set up value in our notify_params struct
 */
const char *value = "Hello! This is a notification!";
if((exit_code = atclient_notify_params_set_value(&notify_params, value)) != 0) {
    goto exit;
}
/*
 * 2. Send the notification
 * We will pass `NULL` for the commit id.
 */
if((exit_code = atclient_notify(&atclient1, &notify_params, NULL)) != 0) {
    goto exit;

Output of this code

[DEBG] 2024-08-13 16:48:13.556642 | connection |        SENT: "soccer0"
[DEBG] 2024-08-13 16:48:13.604292 | connection |        RECV: "3733e916-a5d4-5f5a-b527-a53645304a6c.swarm0002.atsign.zone:6926"
[DEBG] 2024-08-13 16:48:13.958909 | connection |        SENT: "from:soccer0"
[DEBG] 2024-08-13 16:48:13.995959 | connection |        RECV: "data:_ba803d55-725c-44a0-8bdb-28a0d13d8d36@soccer0:684d1175-294e-4c33-a30a-a7d10bddbcd1"
[DEBG] 2024-08-13 16:48:14.050557 | connection |        SENT: "pkam:Eo5l91lZwGOYFH+Oiw+LVKm8c478ox+qwCk4AXssx0TiDZkiqDBCJ7+Q1Va5GLQ9SFeqd/KdF5CscUqKPseG+7OOMJSuBQL9K0IpsqTaG1a170NUOduoQA4q2Sl6jrtXlJsdc47h8mkj8AEk8Sq6PW5c+9W52O6GusqbKM7uhnqhgzgLH9P0VYBY2LSlc061V6lqGDWfsbSyhlII6lrS8a6wubwgNutLSyKCssHvHQy0wmAPGC3Lvm93iiaDBqzKbqBEMJPPL2oTy8Gl9UR+JN2dZLVavHRLr/FweXnVSP8Wc2LIDoxKWS/jRNBr1AudHUyo4yBoPqrxw0gvRd5WOA=="
[DEBG] 2024-08-13 16:48:14.099731 | connection |        RECV: "data:success"
[ERRO] 2024-08-13 16:48:14.099860 | atclient_notify | atclient_string_utils_atsign_with_at failed with code -1
jeremy@raspberrypi8:~/GitHub/at_demos/demos/get_started_c/4b-notify $ cmake -S . -B build && cmake --build build && ./build/main^C
jeremy@raspberrypi8:~/GitHub/at_demos/demos/get_started_c/4b-notify $ ./build/main
[DEBG] 2024-08-13 16:49:00.579611 | connection |        SENT: "soccer0"
[DEBG] 2024-08-13 16:49:00.615765 | connection |        RECV: "3733e916-a5d4-5f5a-b527-a53645304a6c.swarm0002.atsign.zone:6926"
[DEBG] 2024-08-13 16:49:00.932329 | connection |        SENT: "from:soccer0"
[DEBG] 2024-08-13 16:49:00.968379 | connection |        RECV: "data:_ce19738d-6f00-4ef7-b3f2-ee9015f2f022@soccer0:6aeb5cdc-5ca0-46ae-943c-89bf2a873dbc"
[DEBG] 2024-08-13 16:49:01.006703 | connection |        SENT: "pkam:Sur8ExBwZVBf69544TxNB3pfncVlpZwFk05Y0RF49b4bY7sJDqHnnoPaNZbH5zg7hL/mx9NllUQbLwiCl4OKDzWQfL/t0mJiwaPWLjmE0DqFp9UsYwAacrsVWJOp3rRoIMK2lHy8StEIHr1BonXzUFgm9rFfxy/EWNdWsUlqaVubUweFmZPlGX8hq3JfpKwDEr/GhEGZWKi1Y7PebEHsjtcktpiTRPcr3OcdYca6SM1fg9LPf7LrH0iM+bf9JlEtzRZDos3QUOHKujmaKk+t5/GTQzRT4ToFP+D8WBNjdGAJQbMkByd6mpa633nVIf8UOtnvO8mI2/RsHOEz78K39g=="
[DEBG] 2024-08-13 16:49:01.045019 | connection |        RECV: "data:success"
[ERRO] 2024-08-13 16:49:01.045077 | atclient_notify | atclient_string_utils_atsign_with_at failed with code -1

The following code has an atclient_atkey that has not been populated.

The atclient_notify should check if all the necessary atclient_notify_params fields are filled in, including if atclient_atkey has necessary fields filled in before sending the notification.
It should also output an appropriate error message like "notify_params atkey's sharedby field is missing!"