chore: improve terminal options

src/main/resources/i18n/messages_zh_CN.properties

@@ -178,6 +178,9 @@ termora.new-host.terminal.backspace=退格键
 termora.new-host.terminal.character-mode=单字符模式
 termora.new-host.terminal.heartbeat-interval=心跳间隔
 termora.new-host.terminal.startup-commands=启动命令
+termora.new-host.terminal.alt-modifier=Alt 键修饰
+termora.new-host.terminal.alt-modifier.eight-bit=8 位字符
+termora.new-host.terminal.alt-modifier.by-esc=ESC 键作为前缀
 termora.new-host.terminal.env=环境
 termora.new-host.terminal.login-scripts=登录脚本
 termora.new-host.terminal.expect=预期