[MM-29845] Add a new handler to allow authentication via CWS API Key (#16319)

* Add a new handler to allow authentication via CWS API Key

* Make error better

* Add tests and cases for new handler functions

* Move some code around

* Add test for GetCloudSession function

* unset the env after test completion

* Remove white space

* Change Info to Warn

Co-authored-by: Mattermod <mattermod@users.noreply.github.com>

app/authentication.go

@@ -19,6 +19,7 @@ const (
 	TokenLocationHeader
 	TokenLocationCookie
 	TokenLocationQueryString
+	TokenLocationCloudHeader
 )
 
 func (tl TokenLocation) String() string {
@@ -31,6 +32,8 @@ func (tl TokenLocation) String() string {
 		return "Cookie"
 	case TokenLocationQueryString:
 		return "QueryString"
+	case TokenLocationCloudHeader:
+		return "CloudHeader"
 	default:
 		return "Unknown"
 	}
@@ -281,5 +284,9 @@ func ParseAuthTokenFromRequest(r *http.Request) (string, TokenLocation) {
 		return token, TokenLocationQueryString
 	}
 
+	if token := r.Header.Get(model.HEADER_CLOUD_TOKEN); token != "" {
+		return token, TokenLocationCloudHeader
+	}
+
 	return "", TokenLocationNotFound
 }