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>

modules/setting/security.go

@@ -151,7 +151,7 @@ func loadSecurityFrom(rootCfg ConfigProvider) {
 		SecretKey = "!#@FDEWREWR&*("
 	}
 
-	CookieRememberName = sec.Key("COOKIE_REMEMBER_NAME").MustString("gitea_incredible")
+	CookieRememberName = sec.Key("COOKIE_REMEMBER_NAME").MustString("gitea_remember")
 
 	ReverseProxyAuthUser = sec.Key("REVERSE_PROXY_AUTHENTICATION_USER").MustString("X-WEBAUTH-USER")
 	ReverseProxyAuthEmail = sec.Key("REVERSE_PROXY_AUTHENTICATION_EMAIL").MustString("X-WEBAUTH-EMAIL")