Move context from modules to services (#29440)

Since `modules/context` has to depend on `models` and many other
packages, it should be moved from `modules/context` to
`services/context` according to design principles. There is no logic
code change on this PR, only move packages.

- Move `code.gitea.io/gitea/modules/context` to
`code.gitea.io/gitea/services/context`
- Move `code.gitea.io/gitea/modules/contexttest` to
`code.gitea.io/gitea/services/contexttest` because of depending on
context
- Move `code.gitea.io/gitea/modules/upload` to
`code.gitea.io/gitea/services/context/upload` because of depending on
context

modules/context/context_request.go

@@ -1,32 +0,0 @@
-// Copyright 2023 The Gitea Authors. All rights reserved.
-// SPDX-License-Identifier: MIT
-
-package context
-
-import (
-	"io"
-	"net/http"
-	"strings"
-)
-
-// UploadStream returns the request body or the first form file
-// Only form files need to get closed.
-func (ctx *Context) UploadStream() (rd io.ReadCloser, needToClose bool, err error) {
-	contentType := strings.ToLower(ctx.Req.Header.Get("Content-Type"))
-	if strings.HasPrefix(contentType, "application/x-www-form-urlencoded") || strings.HasPrefix(contentType, "multipart/form-data") {
-		if err := ctx.Req.ParseMultipartForm(32 << 20); err != nil {
-			return nil, false, err
-		}
-		if ctx.Req.MultipartForm.File == nil {
-			return nil, false, http.ErrMissingFile
-		}
-		for _, files := range ctx.Req.MultipartForm.File {
-			if len(files) > 0 {
-				r, err := files[0].Open()
-				return r, true, err
-			}
-		}
-		return nil, false, http.ErrMissingFile
-	}
-	return ctx.Req.Body, false, nil
-}