Some settings may be considered sensitive, such as passwords, and storing them
in the configuration file on disk is not good from a security perspective. This change
allows settings to have a special value, `${prompt::text}` or `${prompt::secret}`, to
indicate that elasticsearch should prompt the user for the actual value on startup.
This only works when started in the foreground. In cases where elasticsearch is started
as a service or in the background, an exception will be thrown.
Closes#10838
f6191d05de