Compatibility with simple proposals and custom (+private) proposal fields

[simonaszilinskas]

We should make sure that the module is compatible with two modules that also work with the proposal creation form:
1. Simple proposals

• What the module does: Decidim module that makes the proposal submission process simpler and adds more configuration options to the process.
• Github link: https://github.com/mainio/decidim-module-simple_proposal

2. Custom (+private) proposal fields - Decidim Awesome

• What the module does: Adds custom fields to the proposal. In the case of this specific branch, it even adds the possibility to have private proposal fields.
• Github link: https://github.com/octree-gva/decidim-module-decidim_awesome/tree/feat/awesome_decidim_private_fields

[entantoencuanto]

I have checked the compatibility of 0.28 branch with the modules and:
1. Simple propsosals: The module is compatible using the develop branch of simple proposals.
2. Decidim Awesome: The module is compatible with the current develop branch of decidim awesome, but awesome is not yet adapted to 0.28 in the proposals feature so there are no interferences between the modules currently. I have checked awesome directly because https://github.com/octree-gva/decidim-module-decidim_awesome/tree/feat/awesome_decidim_private_fields is not adapted to 0.28