Auth Provider (#1309)

* auth provider mock interface

* Auth Provider Options

* Implement API Server Auth Package

* Add weh utils

* Add Login URL

* Auth Provider Options

* Add auth provider scope and setting token in cookie

* Remove auth_login_url flag

Co-authored-by: Asim Aslam <asim@aslam.me>
Co-authored-by: Ben Toogood <ben@micro.mu>

auth/provider/oauth/oauth.go

@@ -0,0 +1,42 @@
+package oauth
+
+import (
+	"fmt"
+
+	"github.com/micro/go-micro/v2/auth/provider"
+)
+
+// NewProvider returns an initialised oauth provider
+func NewProvider(opts ...provider.Option) provider.Provider {
+	var options provider.Options
+	for _, o := range opts {
+		o(&options)
+	}
+	return &oauth{options}
+}
+
+type oauth struct {
+	opts provider.Options
+}
+
+func (o *oauth) String() string {
+	return "oauth"
+}
+
+func (o *oauth) Options() provider.Options {
+	return o.opts
+}
+
+func (o *oauth) Endpoint() string {
+	s := fmt.Sprintf("%v?client_id=%v", o.opts.Endpoint, o.opts.ClientID)
+
+	if scope := o.opts.Scope; len(scope) > 0 {
+		s = fmt.Sprintf("%v&scope=%v", s, scope)
+	}
+
+	return s
+}
+
+func (o *oauth) Redirect() string {
+	return o.opts.Redirect
+}