Database Access upstream DB health checks

[smallinsky]

What:

Currently the only way to see if database resource was successfully added is to establish a connection to the databases and if case of failure check the db agent logs.

Teleport DB access can provide a basic health check logic and check if upstream database instance is available by preforming basic health checks like:

• TCP Health Check
• Valid Cloud Credentials check.
• Validate the server-client TLS configuration.

And present it to the user via WebUX, tsh access in readable way. This will allow to provide a easy way to troubleshoot basic db resource misconfiguration issues.

[GavinFrazar]

this would be very useful during database CA rotation. currently, users must reconfigure databases during/after rotation and then they have to manually connect to the database to verify connectivity.