Sanitize custom map SVGs (#16448)

https://github.com/librenms/librenms/security/advisories/GHSA-x8gm-j36p-fppf

Will only sanitize new SVGs. If you have existing backgrounds, they will not be sanitized.
XSS cannot be triggered within the LibreNMS UI, to trigger, you must directly visit the background image URL.

composer.lock

@@ -4,7 +4,7 @@
         "Read more about it at https://getcomposer.org/doc/01-basic-usage.md#installing-dependencies",
         "This file is @generated automatically"
     ],
-    "content-hash": "cfd22f9b26f539a6adc0ee571737bfcf",
+    "content-hash": "fee5d24447dced4397e26066f8c9ee59",
     "packages": [
         {
             "name": "amenadiel/jpgraph",
@@ -1175,6 +1175,51 @@
             ],
             "time": "2023-10-06T06:47:41+00:00"
         },
+        {
+            "name": "enshrined/svg-sanitize",
+            "version": "0.20.0",
+            "source": {
+                "type": "git",
+                "url": "https://github.com/darylldoyle/svg-sanitizer.git",
+                "reference": "068d9fcf912c88a0471d101d95a2caa87c50aee7"
+            },
+            "dist": {
+                "type": "zip",
+                "url": "https://api.github.com/repos/darylldoyle/svg-sanitizer/zipball/068d9fcf912c88a0471d101d95a2caa87c50aee7",
+                "reference": "068d9fcf912c88a0471d101d95a2caa87c50aee7",
+                "shasum": ""
+            },
+            "require": {
+                "ext-dom": "*",
+                "ext-libxml": "*",
+                "php": "^7.1 || ^8.0"
+            },
+            "require-dev": {
+                "phpunit/phpunit": "^6.5 || ^8.5"
+            },
+            "type": "library",
+            "autoload": {
+                "psr-4": {
+                    "enshrined\\svgSanitize\\": "src"
+                }
+            },
+            "notification-url": "https://packagist.org/downloads/",
+            "license": [
+                "GPL-2.0-or-later"
+            ],
+            "authors": [
+                {
+                    "name": "Daryll Doyle",
+                    "email": "daryll@enshrined.co.uk"
+                }
+            ],
+            "description": "An SVG sanitizer for PHP",
+            "support": {
+                "issues": "https://github.com/darylldoyle/svg-sanitizer/issues",
+                "source": "https://github.com/darylldoyle/svg-sanitizer/tree/0.20.0"
+            },
+            "time": "2024-09-05T10:18:12+00:00"
+        },
         {
             "name": "ezyang/htmlpurifier",
             "version": "v4.17.0",