refactor: replace express-ipfilter with lightweight custom middleware (#3917)

This fixes security issue
[CVE-2023-42282](https://github.com/advisories/GHSA-78xj-cgh5-2h22),
which is not very likely to be exploitable in MagicMirror² setups, but
still should be fixed.

The [express-ipfilter](https://www.npmjs.com/package/express-ipfilter)
package depends on the obviously unmaintained
[ip](https://github.com/indutny/node-ip) package, which has known
security vulnerabilities. Since no fix is available, this commit
replaces both dependencies with a custom middleware using the better
maintained [ipaddr.js](https://www.npmjs.com/package/ipaddr.js) library.

Changes:
- Add new `js/ip_access_control.js` with lightweight middleware
- Remove `express-ipfilter` dependency, add `ipaddr.js`
- Update `js/server.js` to use new middleware
- In addition, I have formulated the descriptions of the corresponding
tests a little more clearly.

package.json

@@ -79,11 +79,11 @@
 		"envsub": "^4.1.0",
 		"eslint": "^9.37.0",
 		"express": "^5.1.0",
-		"express-ipfilter": "^1.3.2",
 		"feedme": "^2.0.2",
 		"helmet": "^8.1.0",
 		"html-to-text": "^9.0.5",
 		"iconv-lite": "^0.7.0",
+		"ipaddr.js": "^2.2.0",
 		"moment": "^2.30.1",
 		"moment-timezone": "^0.6.0",
 		"node-ical": "^0.21.0",