feat: Generalize Azure AD support

[cjam]

In your current offering of AzureAD support it assumes that the domain is always going to be login.microsoftonline.com as per usage here:

hasura-auth/src/routes/oauth/config.ts

Lines 89 to 112 in c9b0829

	azuread: {
	grant: {
	oauth: 2,
	scope_delimiter: ' ',
	client_id: process.env.AUTH_PROVIDER_AZUREAD_CLIENT_ID,
	client_secret: process.env.AUTH_PROVIDER_AZUREAD_CLIENT_SECRET,
	authorize_url: `${azureBaseUrl}/[subdomain]/oauth2/authorize`,
	custom_params: {
	prompt: 'select_account',
	},
	access_url: `${azureBaseUrl}/[subdomain]/oauth2/token`,
	profile_url: `${azureBaseUrl}/[subdomain]/openid/userinfo`,
	subdomain: process.env.AUTH_PROVIDER_AZUREAD_TENANT || 'common',
	dynamic: [],
	},
	profile: ({ jwt }) => {
	const payload = jwt?.id_token?.payload;
	return {
	id: payload.oid,
	displayName: payload.name,
	email: payload.email,
	};
	},
	},

My application (nodejs) uses passport-azure-oauth2, which leverages the passport oauth strategy and leaves the base urls as configurable, which allows the library to be used with any azure AD product, in my case Azure b2c which uses a different tenant-based domain entirely.

https://github.com/AndrewKeig/passport-azure-oauth2/blob/85dda56f3b5a71759f7e1995f20fdfe49ec722e1/lib/index.js#L6-L24

It would be great to be able to pass additional configuration to override the base urls / issues / audience that are used in constructing the azure oauth2 flows. Happy to provide additional code if it's helpful.

Originally posted by @cjam in #625 (comment)

[dbarrosop]

Thanks for opening this one, let's take a look after we are done with the other PR but I was thinking in a generic oauth2 connector. The only tricky bit there would be extracting the profile from the provider but maybe we can implement some heuristics there or let the user specify a jsonpath or similar, we can explore a bit later.