Replace thirdparty parse-ms with my own, and add tests

package-lock.json

@@ -13,7 +13,6 @@
         "discord.js": "^14.16.3",
         "dotenv": "^16.4.5",
         "mysql": "^2.18.1",
-        "parse-ms": "^2.1.0",
         "prompt-sync": "^4.2.0",
         "seedrandom": "^3.0.5",
         "sqlite3": "^5.1.6",
@@ -4394,15 +4393,6 @@
         "url": "https://github.com/sponsors/sindresorhus"
       }
     },
-    "node_modules/parse-ms": {
-      "version": "2.1.0",
-      "resolved": "https://registry.npmjs.org/parse-ms/-/parse-ms-2.1.0.tgz",
-      "integrity": "sha512-kHt7kzLoS9VBZfUsiKjv43mr91ea+U05EyKkEtqp7vNbHxmaVuEqN7XxeEVnGrMtYOAxGrDElSi96K7EgO1zCA==",
-      "license": "MIT",
-      "engines": {
-        "node": ">=6"
-      }
-    },
     "node_modules/path-exists": {
       "version": "4.0.0",
       "resolved": "https://registry.npmjs.org/path-exists/-/path-exists-4.0.0.tgz",