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>

modules/web/middleware/data.go

@@ -17,7 +17,7 @@ type ContextDataStore interface {
 
 type ContextData map[string]any
 
-func (ds ContextData) GetData() map[string]any {
+func (ds ContextData) GetData() ContextData {
 	return ds
 }