[Bug] Handle permission error when adding `Include` to `~/.ssh/config`

[peterschmidt85]

Steps to reproduce:

1. Make sure the current user doesn't have permission to write to ~/.ssh/config
2. Run dstack server
3. Create .dstack.yml
4. Run dstack run .

When attaching to the run, the CLI will fail with a permission error when adding Include to ~/.ssh/config.

A possible solution:

1. Make sure the CLI doesn't rely on the Include statement for attaching to the run.
2. Display a clear error message telling how the error will affect the user experience and how to fix it:
   2.1. Make sure the user has write permission
   or
   2.3. When using ssh <run name> include -F <client dstack SHH config path>

[peterschmidt85]

Gonna be fixed in 0.16.1