Include GitHub repo in build

[netmindz]

Update the build of WLED so that during the platformio build their is a python script that looks to extract the git repo URL for the current checkout, then extract the organisation and repo name (the first two parts of the path, e.g wled/wled) as a new value called repo

If git remote branch can not be detected or is not from GitHub.com it should be set to unknown

This value is then included into the build such that it can be returned alongside the release name in the API

[netmindz]

@Moustachauve this will take a while to filter through, but the idea is that a device is able to indicate when it's running a fork of WLED, so updates come from the releases of that repo rather than assuming it's always WLED/WLED, I don't know if it makes sense to also offer the user the option of "vanilla"/"official" releases as well

[Moustachauve]

Yes that's really nice.