luci-lua-runtime: also search luci.dispatcher scope when looking up values
luci-lua-runtime: also search luci.dispatcher scope when looking up values

Some legacy templates access dispatcher functions such as `build_url()`
without explicit scope, which worked in the old runtime since the template
view namespace was instantiated from the dispatcher.

Ensure that this continues to function in the emulated runtime.

Fixes: #6082
Signed-off-by: Jo-Philipp Wich <bd73d35759d75cc215150d1bbc94f1b1078bee01@mein.io>

openwrt/luci,hnyman/luci,openwrt/luci,openwrt/luci,hnyman/luci,openwrt/luci,openwrt/luci,openwrt/luci,hnyman/luci,openwrt/luci,hnyman/luci,hnyman/luci,openwrt/luci,hnyman/luci,hnyman/luci,hnyman/luci