feat: add endpoints to oauth2 provider applications (#11718)

These will show up when configuring the application along with the
client ID and everything else.  Should make it easier to configure the
application, otherwise you will have to go look up the URLs in the
docs (which are not yet written).

Co-authored-by: Steven Masley <stevenmasley@gmail.com>

codersdk/oauth2.go

@@ -14,6 +14,18 @@ type OAuth2ProviderApp struct {
 	Name        string    `json:"name"`
 	CallbackURL string    `json:"callback_url"`
 	Icon        string    `json:"icon"`
+
+	// Endpoints are included in the app response for easier discovery. The OAuth2
+	// spec does not have a defined place to find these (for comparison, OIDC has
+	// a '/.well-known/openid-configuration' endpoint).
+	Endpoints OAuth2AppEndpoints `json:"endpoints"`
+}
+
+type OAuth2AppEndpoints struct {
+	Authorization string `json:"authorization"`
+	Token         string `json:"token"`
+	// DeviceAuth is optional.
+	DeviceAuth string `json:"device_authorization"`
 }
 
 // OAuth2ProviderApps returns the applications configured to authenticate using