Closes#11724.
Option is enabled by default for users using qBittorrent's built-in HTTPS capabilities. This flag will never be set if qBittorrent is using plain HTTP.
Users using HTTPS reverse proxies, like "qbt <-> (http) <-> proxy <-> (https) <-> user" should override the flag in the proxy in order to set it, if they wish to do so.
This cleans up the global namespace by explicitly exporting shared values. All html and JavaScript files have been converted to use explicit exports except for client.js and mocha-init.js
