Feat/fileserver (#60)

* cleanup code for URL type

* fix makefile for trace mode

* refactor, merge Entry, RawEntry and Route into one. 

* Implement fileserver.

* refactor: rename HTTPRoute to ReverseProxyRoute to avoid confusion

* refactor: move metrics logger to middleware package

- fix prometheus metrics for load balanced routes
  - route will now fail when health monitor fail to start

* fix extra output of ls-* commands by defer initializaing stuff, speed up start time

* add test for path traversal attack, small fix on FileServer.Start method

* rename rule.on.bypass to pass

* refactor and fixed map-to-map  deserialization

* updated route loading logic

* schemas: add "add_prefix" option to modify_request middleware


* updated route JSONMarshalling

---------

Co-authored-by: yusing <yusing@6uo.me>

internal/error/utils.go

@@ -40,13 +40,6 @@ func From(err error) Error {
 	return &baseError{err}
 }
 
-func Must[T any](v T, err error) T {
-	if err != nil {
-		LogPanic("must failed", err)
-	}
-	return v
-}
-
 func Join(errors ...error) Error {
 	n := 0
 	for _, err := range errors {