[BUG] Context isolation refactoring

[Durtur]

Require should not be accessible in the renderer scripts due to security reasons. If the window navigates to a malicious site the said site could possibly require and use libraries such as filesystem.

Dungeoneer does not currently navigate to any sites but these libraries should none the less be inaccessible, especially with plugin/mod implementation.

See: https://www.electronjs.org/docs/latest/tutorial/context-isolation