When editing official proposals, title and body appear blank

[tramuntanal]

Describe the bug
A clear and concise description of what the bug is.
When editing official proposals, title and body appear blank although they were filled when creating the proposals.

The problem is in decidim-proposals/app/views/decidim/proposals/admin/proposals/_form.html.erbL8 file. In the mentioned line the value parameter was being passed alone, but then, a new hashtaggable: true parameter was added.
This new parameter provokes an unwanted behavior later in decidim-core/lib/decidim/form_builder.rb#hashtaggable_text_fieldL119 where the value is treated as if it was multi-language with options[:value][locale] but options[:value] is a text field.

The origin of the bug is "Fix proposal creation (#6518)" which was merged during the development of v0.23 so the bug is present in release/0.23-stable and in develop.

To Reproduce
Steps to reproduce the behavior:

1. Create an official proposal filling title and body (which are mandatory anyway)
2. Edit the proposal
3. See the title and body fields blank in the edit view

Expected behavior
A clear and concise description of what you expected to happen.
An admin should be able to see and modify the title and body of an official proposal without loosing its previous contents.

Screenshots
If applicable, add screenshots to help explain your problem.

Stacktrace
If applicable, add the error stacktrace to help explain your problem.

Extra data (please complete the following information):

• Device: [e.g. iPhone6, Desktop]
• Device OS: [e.g. iOS8.1, Windows 10]
• Browser: [e.g. Chrome, Firefox, Safari]
• Decidim Version: [e.g. 0.10]
• Decidim installation: [e.g. MetaDecidim]

Additional context
Add any other context about the problem here. For instance, add Metadecidim link.