chore: make scim auth header case insensitive for 'bearer' (#15538)

Fixes status codes to return more than 500. The way we were using the
package, it always returned a status code 500

enterprise/coderd/scim/scimtypes.go

@@ -1,6 +1,11 @@
 package scim
 
-import "time"
+import (
+	"encoding/json"
+	"time"
+
+	"github.com/imulab/go-scim/pkg/v2/spec"
+)
 
 type ServiceProviderConfig struct {
 	Schemas        []string               `json:"schemas"`
@@ -44,3 +49,37 @@ type AuthenticationScheme struct {
 	SpecURI     string `json:"specUri"`
 	DocURI      string `json:"documentationUri"`
 }
+
+// HTTPError wraps a *spec.Error for correct usage with
+// 'handlerutil.WriteError'. This error type is cursed to be
+// absolutely strange and specific to the SCIM library we use.
+//
+// The library expects *spec.Error to be returned on unwrap, and the
+// internal error description to be returned by a json.Marshal of the
+// top level error.
+type HTTPError struct {
+	scim     *spec.Error
+	internal error
+}
+
+func NewHTTPError(status int, eType string, err error) *HTTPError {
+	return &HTTPError{
+		scim: &spec.Error{
+			Status: status,
+			Type:   eType,
+		},
+		internal: err,
+	}
+}
+
+func (e HTTPError) Error() string {
+	return e.internal.Error()
+}
+
+func (e HTTPError) MarshalJSON() ([]byte, error) {
+	return json.Marshal(e.internal)
+}
+
+func (e HTTPError) Unwrap() error {
+	return e.scim
+}