config: respect includes in protected config

config: respect includes in protected config

Protected config is implemented by reading a fixed set of paths,
which ignores config [include]-s. Replace this implementation with a
call to config_with_options(), which handles [include]-s and saves us
from duplicating the logic of 1) identifying which paths to read and 2)
reading command line config.

As a result, git_configset_add_parameters() is unused, so remove it. It
was introduced alongside protected config in 5b3c650777 (config: learn
`git_protected_config()`, 2022-07-14) as a way to handle command line
config.

Signed-off-by: Glen Choo <chooglen@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>