feat: send test mail (#7968)

# Which Problems Are Solved

- Zitadel doesn't have a way to test SMTP settings either before
creating a new provider or once the SMTP provider has been created.
- Zitadel SMTP messages can be more informative for usual errors

# How the Problems Are Solved

- A new step is added to the new/update SMTP provider wizard that allows
us to test a configuration. The result is shown in a text area.
- From the table of SMTP providers you can test your settings too.
- The email address to send the email is by default the email address
for the logged in user as suggested.
- Some of the SMTP error messages have been changed to give more
information about the possible situation. For example: could not contact
with the SMTP server, check the port, firewall issues... instead of
could not dial

Here's a video showing this new option in action:


https://github.com/zitadel/zitadel/assets/30386061/50128ba1-c9fa-4481-8eec-e79a3ca69bda

# Additional Changes

Replace this example text with a concise list of additional changes that
this PR introduces, that are not directly solving the initial problem
but are related.
For example:
- The docs explicitly describe that the property XY is mandatory
- Adds missing translations for validations.

# Additional Context

- Closes #4504

internal/static/i18n/zh.yaml

@@ -53,11 +53,24 @@ Errors:
     NotFound: 未找到 SMS 配置
     AlreadyActive: SMS 配置已启用
     AlreadyDeactivated: SMS 配置已停用
+  SMTP:
+    NotEmailMessage: 消息不是电子邮件消息
+    RequiredAttributes: 必须设置主题、收件人和内容，但部分或全部为空
+    CouldNotSplit: 无法拆分主机和端口以连接到 smtp
+    CouldNotDial: 无法与 SMTP 服务器联系，请检查端口、防火墙问题...
+    CouldNotDialTLS: 无法使用 TLS 与 SMTP 服务器联系，请检查端口、防火墙问题...
+    CouldNotCreateClient: 无法创建 smtp 客户端
+    CouldNotStartTLS: 无法启动 tls
+    CouldNotAuth: 无法添加 smtp 身份验证，请检查您的用户名和密码是否正确，如果正确，可能您的提供商需要 ZITADEL 不支持的身份验证方法
+    CouldNotSetSender: 无法设置发件人
+    CouldNotSetRecipient: 无法设置收件人
   SMTPConfig:
+    TestPassword: 未找到测试密码
     NotFound: 未找到 SMTP 配置
     AlreadyExists: SMTP 配置已存在
     AlreadyDeactivated: SMTP 配置已停用
     SenderAdressNotCustomDomain: 发件人地址必须在在实例的域名设置中验证。
+    TestEmailNotFound: 找不到用于测试的电子邮件地址
   Notification:
     NoDomain: 未找到对应的域名
   User: