Switch product configs from make to ckati

This speeds up dumping make variables from ~380ms using make to ~220ms
using ckati. It also means that we're consistently using the same parser
for builds (with the same .KATI_READONLY/etc extensions).

envsetup.sh (lunch) / other scripts still use make, changing those to go
through soong_ui will be a future change.

Test: m clean; m nothing
Test: USE_GOMA=true m nothing
Test: m PRODUCT-aosp_x86-sdk
Test: m APP-Calculator
Test: build/soong/build_test.bash -only-config  (on AOSP and internal master)
Change-Id: I6ca554de8de4955fb869001d06d29969b75751cc
diff --git a/ui/build/build.go b/ui/build/build.go
index 45d18e0..0df22b3 100644
--- a/ui/build/build.go
+++ b/ui/build/build.go
@@ -104,7 +104,7 @@
 
 func help(ctx Context, config Config, what int) {
 	cmd := Command(ctx, config, "help.sh", "build/make/help.sh")
-	cmd.Sandbox = makeSandbox
+	cmd.Sandbox = dumpvarsSandbox
 	cmd.Stdout = ctx.Stdout()
 	cmd.Stderr = ctx.Stderr()
 	cmd.RunOrFatal()