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_test.go

@@ -0,0 +1,24 @@
+// Copyright 2023 The Gitea Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+
+package context
+
+import (
+	"net/http"
+	"net/http/httptest"
+	"testing"
+
+	"code.gitea.io/gitea/modules/setting"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestRemoveSessionCookieHeader(t *testing.T) {
+	w := httptest.NewRecorder()
+	w.Header().Add("Set-Cookie", (&http.Cookie{Name: setting.SessionConfig.CookieName, Value: "foo"}).String())
+	w.Header().Add("Set-Cookie", (&http.Cookie{Name: "other", Value: "bar"}).String())
+	assert.Len(t, w.Header().Values("Set-Cookie"), 2)
+	removeSessionCookieHeader(w)
+	assert.Len(t, w.Header().Values("Set-Cookie"), 1)
+	assert.Contains(t, "other=bar", w.Header().Get("Set-Cookie"))
+}