Fix template chaining to be more DRY

assets/package.json

wdfn-server/waterdata/templates/base.html

wdfn-server/waterdata/templates/base_network.html

wdfn-server/waterdata/templates/base_plain.html

wdfn-server/waterdata/templates/base_plain_network.html

...server/waterdata/templates/monitoring_location_embed.html

wdfn-server/waterdata/templates/partials/base.html

wdfn-server/waterdata/templates/states_counties.html