Simplify calls to allowed_to?

[sauloperez]

Due to Decidim::NeedsPermission#allowed_to?'s signature, we cannot pass in a user argument other than current_user without first passing extra_context and chain, even though we still want to use their defaults.

As a consequence, the calls to this method duplicate the permission_class_chain coupling views and other objects to it, which results in long lines and hampers changeability.

A potential solution could be to change #allowed_to? to use keyboard arguments instead so we can pass user only. If we do so, it needs to be a backward compatible-change for Decidim to accept it.

In the meantime, we could prepend somehow our own permissions class in https://github.com/decidim/decidim/blob/develop/decidim-consultations/app/controllers/decidim/consultations/application_controller.rb#L10-L13. If we go with the approach outlined in #19 of having our own controllers, we could just register a different chain that includes this new permissions class.

Originally posted by @microstudi in #15 (comment)

[sauloperez]

https://github.com/coopdevs/decidim-module-action_delegator/pull/42/files#diff-29d877fefa73ca09ce9d760a2aa4b1c0R11 is yet another example that needs solving.

[sauloperez]

https://github.com/coopdevs/decidim-module-action_delegator/pull/49/files#diff-9b3fbee9f91d51262226647e0d00214b1abcc5942b5436639e514f3e62a1b460 is a great example of how this can be solved by having our own controller so we have control over the permissions chain.