[#65294674] govuk_node_list hyphen compat
[#65294674] govuk_node_list hyphen compat

Provide backwards compatibility for node classes with hyphens in their
names because gds/alphagov-deployment has `server_class` references like
`whitehall-frontend` and `calculators-frontend`.

This commit should be reverted when those have been changed.

alphagov/govuk-puppet,alphagov/govuk-puppet,alphagov/govuk-puppet,alphagov/govuk-puppet,alphagov/govuk-puppet,alphagov/govuk-puppet