Add core property for setting quiet.

[dadgar]

Changes proposed in this PR:

Add a property to disable prompting. This is useful when scripting using HCP.

How I've tested this PR:

I set the property and ran a command that outputs additional output. When set to true, the output was omitted and when false or unset the help output was shown.

Also checked that the hcp profile set --help output shows the new property.

$ echo -n "test" | hcp vs secrets create quiet_test --data-file=-
Secret Name   Latest Version   Created At
quiet_test   1                2024-06-21T23:55:39.442Z

✓ Successfully created secret with name "quiet_test"

To read your secret, run:
  $ hcp vault-secrets secrets read quiet_test6 --app cli

$ hcp profile set core/quiet true
✓ Property "core/quiet" updated

$ echo -n "t" | hcp vs secrets create quiet_test2 --data-file=-
Secret Name   Latest Version   Created At
quiet_test2   1                2024-06-21T23:55:51.291Z

How I expect reviewers to test this PR:

Code review.

Checklist:

• Tests added if applicable
• CHANGELOG entry added or label 'pr/no-changelog' added to PR

  Run CHANGELOG_PR=<PR number> make changelog/new-entry for guidance
  in authoring a changelog entry, and commit the resulting file, which should
  have a name matching your PR number. Entries should use imperative present
  tense (e.g. Add support for...)