fix: auth_cli enrollment saves non-named atKeys file

[Xlin123]

Describe the bug

~/.local/bin/at_activate enroll -a @bagel69 -s passcode-p noports -d apaz -k ~/.atsign/keys/

[Success] Your .atKeys file saved at /home/avlazure/.atsign/keys/.atKeys

Steps to reproduce

Go through the APKAM flow and supply -k with a directory.

Expected behavior

generates either @bagel69_key.atKeys or something along those lines.

@gkc mentioned:

I decided to make -k mandatory because of the dangers inherent in testing situations where the "original" keys are in ~/.atsign/keys and then you accidentally overwrite. I think I added protection so it'll fail if the file exists but it felt safer overall just to make the user conscious of where the keys files would go

Screenshots

No response

Smartphones

No response

Were you using an atApplication when the bug was found?

No response

Additional context

No response

[srieteja]

waiting for PR review. Carrying it forward to PR93

[srieteja]

Closing this as the same issue is solved in #629