Unsupported provider in allauth? Try openid_connect

I am currently doing some work for a client to integrate Xero (accounting platform) into my client's Django app. Xero is not listed as a supported provider listed in allauth's documentation so I rolled up my sleeves and prepared a working custom provider, then started a draft PR upstream last week.

Then Raymond yesterday asked if this could be achieved with allauth's openid_connect (OIDC) provider, which upon closer inspection is a more generic provider that can deal with websites that support it. After a day changing the config, fixing a few bugs, it turns out that this worked and my custom provider will not be required.

I have suggested some documentation updates which I will happily do the work for if Raymond likes the idea which is to essentially highlight the openid_connect provider more prominently. The lesson here is to check the generic providers within allauth before charging ahead with a custom provider.