luci-lua-runtime: render cbi header/footer templates via ucode runtime

Trigger rendering of CBI header and footer templates via the ucode runtime
`include()` in order to ensure that scope data is properly inherited from
Lua templates (`cbi/header`) including ucode templates (`header`).

This fixes automatic triggering of the config apply flow on legacy Lua CBI
forms.

Ref: https://github.com/openwrt/luci/pull/6056#issuecomment-1292396588
Signed-off-by: Jo-Philipp Wich <jo@mein.io>