Syslog sink over http for logstash (or any json source) (#14424)

* inital commit of a new syslog sink over http

* cosmetics

* cosmetics fix...

* cosmetic fix again

* cosmetics fix again

* its nice now...

* add non blocking option

* Syslog Sink integrated as API PUT method

* lint fix

* Update includes/html/api_functions.inc.php

Co-authored-by: Tony Murray <murraytony@gmail.com>

* Update includes/html/api_functions.inc.php

Co-authored-by: Tony Murray <murraytony@gmail.com>

* Update includes/html/api_functions.inc.php

Co-authored-by: Tony Murray <murraytony@gmail.com>

* change to POST, fix decoding issue and json exception

* logstash/json documentation added. syslog documentation a bit re-structured

* lint fix

---------

Co-authored-by: Tony Murray <murraytony@gmail.com>

doc/API/Logs.md

@@ -75,3 +75,34 @@ Output:
     ]
 }
 ```
+
+### `syslogsink`
+
+Route: `/api/v0/logs/syslogsink`
+
+Accept any json messages and passes to further syslog processing. single messages or an array of multiple messages is accepted. see [Syslog](../Extensions/Syslog.md) for more details and logstash integration
+
+
+Example
+```
+curl -L -X POST 'https://sink.librenms.org/api/v0/syslogsink/' -H 'X-Auth-Token: xxxxxxxLibreNMSApiToken' --data-raw '[   
+    {
+        "msg": "kernel: minimum Message",
+        "host": "mydevice.fqdn.com"
+    },
+    {
+        "msg": "Line protocol on Interface GigabitEthernet1/0/41, changed state to up",
+        "facility": 23,
+        "priority": "189",
+        "program": "LINEPROTO-5-UPDOWN",
+        "host": "172.29.10.24",
+        "@timestamp": "2022-12-01T20:14:28.257Z",
+        "severity": 5,
+        "level": "ERROR"
+    },
+    {
+        "msg": "kernel: a unknown host",
+        "host": "unknown.fqdn.com"
+    }
+]'
+```