Implement specific *all functions

Specific `_*all` and `_*all_with` functions were implemented to make
the API more concise and clean, and to replace the use of
`RELAY_CHN_ID_ALL`, which caused confusion within the API.

Refs #1085

src/relay_chn_core.c

@@ -407,7 +407,7 @@ void relay_chn_issue_cmd(relay_chn_ctl_t* chn_ctl, relay_chn_cmd_t cmd)
 #if CONFIG_RELAY_CHN_COUNT > 1
 bool relay_chn_is_channel_id_valid(uint8_t chn_id)
 {
-    bool valid = (chn_id < CONFIG_RELAY_CHN_COUNT) || chn_id == RELAY_CHN_ID_ALL;
+    bool valid = chn_id < CONFIG_RELAY_CHN_COUNT;
     if (!valid) {
         ESP_LOGE(TAG, "Invalid channel ID: %d", chn_id);
     }