oauth2 clientcredentials

[rizzza]

Summary

• oauth2x package to handle viper flags, config, tokensource, and client

Usage

Appconfig will look like this

// OIDCClientConfig stores the configuration for an OIDC client
type OIDCClientConfig struct {
	Client oauth2x.Config
}

var AppConfig struct {
	Events  EventsConfig
	Logging loggingx.Config
	OIDC    OIDCClientConfig
}

and export environment like so

SERVICE_OIDC_CLIENT_ID=someclientid 
SERVICE_OIDC_CLIENT_SECRET=clientsecret  
SERVICE_OIDC_CLIENT_TOKEN_URL=http://iam.dev/token