Fixed snmptraps. (#8898)

* Fixed snmptraps.

* Fixed space

* Added bgp down/up and authentication failure

* Fixed typo

* Fixed some typos, arrays, astext and format_hostname

* Updated documentation

* Moved code to a function

* Some refactor

* Minor fixes

* Minor fixes 2

* More minor fixes

* Changes requested by Tony

* Minor fixes

* Moved include to snmptrap.php

* Refactor traps to use object oriented code.

Should trigger events too/instead, but we'll leave that.
Testing todo

* Add tests and fix things so they actually work
Not checking events yet.

* Fixed typo and severity level

* Update composer deps, I think the lock file wasn't right.
add json and mbstring extension deps while I'm at it.

* Fix several issues with phpunit fixtures

includes/snmptrap.inc.php

@@ -0,0 +1,16 @@
+<?php
+
+use LibreNMS\Config;
+
+function process_trap($device, $entry)
+{
+    $oid = trim(strstr($entry[3], " "));
+    $oid = str_replace("::", "", strstr($oid, "::"));
+
+    $file = Config::get('install_dir').'/includes/snmptrap/'.$oid.'.inc.php';
+    if (is_file($file)) {
+        include $file;
+    } else {
+        echo "unknown trap ($file)";
+    }
+}