feat(wrapperModules.mangowc): reload with new config after build

[WeraPea]

Adds mango-reload.service which reloads mango with new config after building, based on #496.

Differs from niri's implementation by the fact that it uses a standalone service and requires users to start that service themself, as mango doesn't provide a systemd service.

Currently requires git version of mango as 0.15 with the required load_config_file dispatch has not released yet.

[wyndon]

I'm not sure how to use this. I've patched my input to include this PR, but I don't have a mango-reload.service that I can start.

[WeraPea]

I'm not sure how to use this. I've patched my input to include this PR, but I don't have a mango-reload.service that I can start.

For the service to be picked up by systemd you need to add mango to systemd packages with:

systemd.packages = [ config.wrappers.mango.wrapper ];