Revert "loader/lua: Remove pager shim"

This reverts commit 8b9178cd0d.

Really old loader.efi files persist in the field. Revert this to support
it. We need to support this through at least 14.2 now, alas.

MFC After:		3 days
Sponsored by:		Netflix
Reviewed by:		kevans
Differential Revision:	https://reviews.freebsd.org/D45881

(cherry picked from commit b38a82c77a)

stand/lua/cli.lua

@@ -30,6 +30,18 @@ local core = require("core")
 
 local cli = {}
 
+if not pager then
+	-- shim for the pager module that just doesn't do it.
+	-- XXX Remove after 12.2 goes EoL.
+	pager = {
+		open = function() end,
+		close = function() end,
+		output = function(str)
+			printc(str)
+		end,
+	}
+end
+
 -- Internal function
 -- Parses arguments to boot and returns two values: kernel_name, argstr
 -- Defaults to nil and "" respectively.