Refactor web package and context package (#25298)

1. The "web" package shouldn't depends on "modules/context" package,
instead, let each "web context" register themselves to the "web"
package.
2. The old Init/Free doesn't make sense, so simplify it
* The ctx in "Init(ctx)" is never used, and shouldn't be used that way
* The "Free" is never called and shouldn't be called because the SSPI
instance is shared

---------

Co-authored-by: Giteabot <teabot@gitea.io>

services/auth/interface.go

@@ -29,26 +29,11 @@ type Method interface {
 	Verify(http *http.Request, w http.ResponseWriter, store DataStore, sess SessionStore) (*user_model.User, error)
 }
 
-// Initializable represents a structure that requires initialization
-// It usually should only be called once before anything else is called
-type Initializable interface {
-	// Init should be called exactly once before using any of the other methods,
-	// in order to allow the plugin to allocate necessary resources
-	Init(ctx context.Context) error
-}
-
 // Named represents a named thing
 type Named interface {
 	Name() string
 }
 
-// Freeable represents a structure that is required to be freed
-type Freeable interface {
-	// Free should be called exactly once before application closes, in order to
-	// give chance to the plugin to free any allocated resources
-	Free() error
-}
-
 // PasswordAuthenticator represents a source of authentication
 type PasswordAuthenticator interface {
 	Authenticate(user *user_model.User, login, password string) (*user_model.User, error)