Breaking: Migrate extension to the new ESM system of GNOME 45

Migrate with the help of, among others, the following resources:
https://blogs.gnome.org/shell-dev/2023/09/02/extensions-in-gnome-45/
https://gjs.guide/extensions/upgrading/gnome-shell-45.html

Only support GNOME Shell version 45, since only 45 is compatible with
the new ESM system.

Since panel._originalAddToPanelBox is no longer valid, just overwrite
using the prototype on disable.

Add "sourceType": "module" to eslintrc.yml to get rid of:
"Parsing error: 'import' and 'export' may appear only with 'sourceType:
module'"
See here:
https://eslint.org/docs/latest/use/configure/language-options#specifying-parser-options

.eslintrc.yml

@@ -3,6 +3,7 @@ env:
 extends: 'eslint:recommended'
 parserOptions:
   ecmaVersion: 2022
+  sourceType: module
 rules:
   indent:
     - error
@@ -49,5 +50,4 @@ rules:
     - error
     - always
 globals:
-  imports: readonly
   log: readonly