Fix encrypt command output when using --stdin-name (#65122)

* Fix encrypt command output when using --stdin-name

Add a new line after reading input if input doesn't end with a new line

* Only print is we're in a tty

* Add changelog fragment

changelogs/fragments/65122-fix-encrypt_string-stdin-name-ouput-tty.yml

@@ -0,0 +1,2 @@
+bugfixes:
+  - ansible-vault - Fix ``encrypt_string`` output in a tty when using ``--sdtin-name`` option (https://github.com/ansible/ansible/issues/65121)

lib/ansible/cli/vault.py

@@ -318,6 +318,9 @@ class VaultCLI(CLI):
             if stdin_text == '':
                 raise AnsibleOptionsError('stdin was empty, not encrypting')
 
+            if sys.stdout.isatty() and not stdin_text.endswith("\n"):
+                display.display("\n")
+
             b_plaintext = to_bytes(stdin_text)
 
             # defaults to None