This module generates a `.ssh/config` file. This doesn't embed _all_
options for the ssh client, but the most common ones should be there.
Example usage:
```nix
programs.ssh = {
enable = true;
forwardAgent = true;
controlMaster = "auto";
matchBlocks = [
{
host = "something.blah.edu";
port = 1024;
user = "cleague";
identitiesOnly = true;
}
{
host = "host1 host2 host2.net host2.com";
port = 7422;
hostname = "example.com";
serverAliveInterval = 60;
}
{
host = "lucian";
forwardX11 = true;
forwardX11Trusted = true;
checkHostIP = false;
};
};
};
```
Each entry in `programs.ssh.matchBlocks` must contain a `host` field,
which will be used for the block condition.
For example, with these settings Bash will complain if uninitialized
variables are used. Some code has been improved to run cleanly with
these settings.
If the dconf service hasn't been installed then the configuration
activation will fail. Thus, make sure the activation script is run after
packages have been installed.
