Add PreUp, PostUp, PreDown, PostDown for client (#1714)

* Fix create client popup background is not white

* Fix no Add button when client Allowed Ips or Server Allowed Ips is empty

* Add preUp preDown postUp postDown for client

* Add description of hooks for client config

* Move hooks's label text into 'hooks' in en.json

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Co-authored-by: yanghuanglin <yanghuanglin@qq.com>
Co-authored-by: Bernd Storath <999999bst@gmail.com>

src/server/database/migrations/0000_short_skin.sql

@@ -4,6 +4,10 @@ CREATE TABLE `clients_table` (
 	`name` text NOT NULL,
 	`ipv4_address` text NOT NULL,
 	`ipv6_address` text NOT NULL,
+	`pre_up` text DEFAULT '' NOT NULL,
+	`post_up` text DEFAULT '' NOT NULL,
+	`pre_down` text DEFAULT '' NOT NULL,
+	`post_down` text DEFAULT '' NOT NULL,
 	`private_key` text NOT NULL,
 	`public_key` text NOT NULL,
 	`pre_shared_key` text NOT NULL,