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

services/context/context_cookie.go

@@ -0,0 +1,42 @@
+// Copyright 2023 The Gitea Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+
+package context
+
+import (
+	"net/http"
+	"strings"
+
+	"code.gitea.io/gitea/modules/setting"
+	"code.gitea.io/gitea/modules/web/middleware"
+)
+
+const CookieNameFlash = "gitea_flash"
+
+func removeSessionCookieHeader(w http.ResponseWriter) {
+	cookies := w.Header()["Set-Cookie"]
+	w.Header().Del("Set-Cookie")
+	for _, cookie := range cookies {
+		if strings.HasPrefix(cookie, setting.SessionConfig.CookieName+"=") {
+			continue
+		}
+		w.Header().Add("Set-Cookie", cookie)
+	}
+}
+
+// SetSiteCookie convenience function to set most cookies consistently
+// CSRF and a few others are the exception here
+func (ctx *Context) SetSiteCookie(name, value string, maxAge int) {
+	middleware.SetSiteCookie(ctx.Resp, name, value, maxAge)
+}
+
+// DeleteSiteCookie convenience function to delete most cookies consistently
+// CSRF and a few others are the exception here
+func (ctx *Context) DeleteSiteCookie(name string) {
+	middleware.SetSiteCookie(ctx.Resp, name, "", -1)
+}
+
+// GetSiteCookie returns given cookie value from request header.
+func (ctx *Context) GetSiteCookie(name string) string {
+	return middleware.GetSiteCookie(ctx.Req, name)
+}