Why:
When there is not Budget accepting (Investment creation) the guide page
doesn't have much sense as it will give the user an option that can't be
used (creating an Investment).
How:
Using `Budget.current&.accepting?` conditional at GuidesHelper to link
to new proposal link instead of guide page, and adding an scenario to
guides feature spec for it.
During a Participatory Budget, some users are getting confused and
creating a proposal instead of a budget investment. This intermediate
page should help them create investments
Adding a feature flag just in case other forks don’t need this feature
and setting seeds and dev_seeds for appropriate initial setup