[BUG]Web interface buttons stop responding in FireFox

[fastbike]

Describe the bug
The buttons on the web interface stop responding after page has become inactive

To Reproduce
Open the web server in FireFox, navigate away to a separate tab after the page loads. Switch back after using other pages, the timeout will depend on how many other tabs you have loaded. SM such as Discord uses lots of memory so FF will unload inactive pages, which means the scripts on the BE page are no longer available.

Expected behavior
Buttons respond e.g. "Change Settings" shows the settings page

Screenshots
The browser developer tools page shows the error

Version and settings (please complete the following information):

• Please attach screenshot of configuration for easier debugging
• Software version: 9.3.2
• Battery used: Nissan LEAF
• Inverter communication protocol: BYD Modbus
• Hardware used for Battery-Emulator: Stark CMR
• GPIO controlled contactors: yes
• MQTT: yes

I have not tested this in other browsers. This is a different behaviour to earlier versions.

[fastbike]

The FF docs give some background.
https://firefox-source-docs.mozilla.org/browser/tabunloader/
We should be reloading the scripts when the page is reactivated. The periodic page refresh does not do this.