luci-app-snmpd: convert CBI to JS

Eliminates luci-compat, but no other changes.

Signed-off-by: Karl Palsson <karlp@etactica.com>
[add final newline, explicitly require `view` class, remove unused require,
 fix commit subject, initialize translation template]
Signed-off-by: Jo-Philipp Wich <jo@mein.io>