Added support for newer mongoose versions

-Mongoose and mongodb dependencies have been updated to the most recent versions in package.json
-Updated the project for use with the newest mongoose major version which required fixing many breaking changes to a number of files in the explorer
-Removed the db.find_address_tx() function as it is unused

NOTE: This update requires mongoose 6.0.10 or higher. If you are getting errors running the explorer after upgrading, it is recommended to run an 'npm update' or manually update mongoose to a more modern version which should fix the problem

package.json

@@ -38,8 +38,8 @@
     "express": ">=4.18.1",
     "intl": "^1.2.5",
     "jsonminify": "^0.4.2",
-    "mongodb": "^4.7.0",
-    "mongoose": "^6.3.6",
+    "mongodb": "^5.4.0",
+    "mongoose": "^7.1.0",
     "morgan": ">=1.10.0",
     "postman-request": "^2.88.1-postman.31",
     "pug": "~3.0.2",