Login page internationalisation (#5765)

* Load locale strings in login page
* Generate and use login locale strings
* Add makefile target
* Update workflow
* Update build dockerfiles
* Add missing default string

internal/api/server.go

@@ -41,10 +41,11 @@ import (
 )
 
 const (
-	loginEndpoint      = "/login"
-	logoutEndpoint     = "/logout"
-	gqlEndpoint        = "/graphql"
-	playgroundEndpoint = "/playground"
+	loginEndpoint       = "/login"
+	loginLocaleEndpoint = loginEndpoint + "/locale"
+	logoutEndpoint      = "/logout"
+	gqlEndpoint         = "/graphql"
+	playgroundEndpoint  = "/playground"
 )
 
 type Server struct {
@@ -228,6 +229,7 @@ func Initialize() (*Server, error) {
 	r.Get(loginEndpoint, handleLogin())
 	r.Post(loginEndpoint, handleLoginPost())
 	r.Get(logoutEndpoint, handleLogout())
+	r.Get(loginLocaleEndpoint, handleLoginLocale(cfg))
 	r.HandleFunc(loginEndpoint+"/*", func(w http.ResponseWriter, r *http.Request) {
 		r.URL.Path = strings.TrimPrefix(r.URL.Path, loginEndpoint)
 		w.Header().Set("Cache-Control", "no-cache")