refactor!: move go-chi/session into Gitea (#39504)

The `gitea.com/go-chi/session` package only exists for Gitea, so it
moves into `modules/session` to fix its bugs directly. Fixes the flake
in
https://github.com/go-gitea/gitea/actions/runs/36726154500/job/109923538400.

- Sessions are only written back when changed, so a read-only request
can't revert a concurrent change or restore a logged-out session, like
https://github.com/go-macaron/session/commit/ae808a4a4660c802965c834299ab08f167effd12
- The session cookie is only set once a session holds data
- Every backend refreshes the expiry on load and file sessions are
written atomically
- Also fix  https://github.com/go-gitea/gitea/issues/36176

## ⚠️ BREAKING ⚠️

* the `mysql`, `postgres`, `couchbase` and `memcache` session providers
are removed, use `file`, `db` or `redis` instead
* login-related cookies are renamed to `gitea_session` and
`gitea_remember`, if you'd like to use the old names, set `COOKIE_NAME`
and `COOKIE_REMEMBER_NAME` in app.ini

---------

Co-authored-by: wxiaoguang <wxiaoguang@gmail.com>

routers/web/auth/auth.go

@@ -444,7 +444,9 @@ func extractUserNameFromOAuth2(gothUser *goth.User) (string, error) {
 // HandleSignOut resets the session and sets the cookies
 func HandleSignOut(ctx *context.Context) {
 	_ = ctx.Session.Flush()
-	_ = ctx.Session.Destroy(ctx.Resp, ctx.Req)
+	if err := ctx.Session.Destroy(ctx.Resp, ctx.Req); err != nil {
+		log.Error("Unable to destroy session: %v", err)
+	}
 	ctx.DeleteSiteCookie(setting.CookieRememberName)
 	middleware.DeleteRedirectToCookie(ctx.Resp)
 }
@@ -931,10 +933,8 @@ func ActivateEmail(ctx *context.Context) {
 }
 
 func regenerateSession(ctx *context.Context, updates map[string]any) error {
-	if _, err := session.RegenerateSession(ctx.Resp, ctx.Req); err != nil {
-		return fmt.Errorf("regenerate session: %w", err)
-	}
 	sess := ctx.Session
+	sess.Regenerate(ctx.Resp, ctx.Req)
 	sessID := sess.ID()
 	for k, v := range updates {
 		if err := sess.Set(k, v); err != nil {