Disable ssh_key_pair generation when an existing keypair is being passed in

[BGarber42]

what

• If you're passing in a keypair name, don't generate one, and done try to load a local file that doesn't exist

why

• You want to use an existing keypair
• You don't want plan to fail.

references

• https://gist.github.com/BGarber42/d2710437f649c1d8908b3f6bc602adde

[nitrocode]

Thank you for your contribution.

In our bastion component, we use an additional ssh key enabled toggle and pass that in to explicitly enable and disable the module itself.

This method also works. Please see comments.

[nitrocode]

/test all

[mergify]

This pull request is now in conflict. Could you fix it @BGarber42? 🙏

[nitrocode]

/test all

[hans-d]

/terratest