lualoader: cli: add read-conf

This is a straightforward match to the command used by many in forthloader;
it uses the newly-exported config.readConfFiles() to make sure that any
loader_conf_files gets done as appropriate.

PR:		244640
Submitted by:	Olivier Certner <olivier freebsd free fr>
MFC after:	3 days

stand/lua/cli.lua

@@ -125,6 +125,11 @@ cli['boot-conf'] = function(...)
 	core.autoboot(argstr)
 end
 
+cli['read-conf'] = function(...)
+	local _, argv = cli.arguments(...)
+	config.readConfFiles(assert(core.popFrontTable(argv)), {})
+end
+
 cli['reload-conf'] = function(...)
 	config.reload()
 end