[Feature request] Allow configuration through Firefox policies

I can't define default options for the extension. The only apparent way to be able to copy configurations over to other machines is to download the backup JSON file from the extension's configuration page and then manually restore using that file.

uBlock supports configuration through policies, and I was wondering if I'm doing something wrong or if this isn't currently possible with Vimium. There's even a GitHub page by Mozilla using uBlock as an example.

I should note that I am using Home Manager, though it works just fine for uBlock and other policy configurations.

To Reproduce

1. Try to define policy with contents of backed up vimium-options.json file, or even just a single option like scrollStepSize (either through Nix or normally).
2. Vimium does not load the configuration.

See "3rdparty".Extensions; the other options are unimportant:

Browser and Vimium version

Firefox version 133.0.3 on Linux 6.12.7 #1-NixOS SMP PREEMPT_DYNAMIC Fri Dec 27 13:02:20 UTC 2024

Vimium version 2.1.2

Start by locating Vimium’s Firefox-specific configuration loading and options initialization, then compare them with the Firefox policy shape linked in the issue. Done means a policy containing the backed-up options or a single option such as scrollStepSize is loaded by Vimium; add or run a focused regression check if the repository has one.