Switch envsetup.sh dumpvars to soong_ui

Use soong_ui instead of make&config.mk directly. This way we use a
consistent make parser and sandboxing configurations.

Test: printconfig
Test: get_build_var TARGET_DEVICE
Test: get_abs_build_var PRODUCT_OUT
Test: get_abs_build_var ALL_PRODUCTS
Test: lunch aosp_marlin-userdebug
Test: build_build_var_cache; set | grep var_cache (diff before/after)
Change-Id: I22abdf95669b7a4fb8162377e013a9013155f249