feat: proxy auth support (#485)

* Change the order of commands to be able to cache more layers in case of multiple builds triggered in a row

* Fix #471

* Format Code

* Revert "Change the order of commands to be able to cache more layers in case of multiple builds triggered in a row"

This reverts commit 01362f34ee.

* Adjustment based on the review

* Rename "login-header" to "loginHeader" and prepare auth.method to accept "none" as a value

* Fixed line break

* Readd "lumberjack.v2" import which was removed by gofmt

Sorry - I do my tests and run "gofmt" before comitting the changes - It sadly seems like it is messing up the imports over and over again.

doc.go

@@ -16,6 +16,10 @@ to import "github.com/filebrowser/filebrowser/bolt".
 
 	m := &fm.FileBrowser{
 		NoAuth: false,
+		Auth: {
+			Method: "default",
+			LoginHeader: "X-Fowarded-User"
+		},
 		DefaultUser: &fm.User{
 			AllowCommands: true,
 			AllowEdit:     true,