Ability to create blog posts as a user group

**Is your feature request related to a problem? Please describe.**

Right now the blog posts are always displayed as written by the user who created them. Some users would like to create the blog posts as one of the groups they belong to, similarly as you can create proposals as a group for instance.

**Describe the solution you'd like**

I'd like to have a dropdown for selecting the blog post author when creating a new blog post. Similarly to when creating the proposals, the dropdown should show:

• The current user's personal account (default functionality, as is right now)
• All the groups the user is a member in (similarly to proposals)

**Describe alternatives you've considered**

Login to the server, modify the author of the blog post from the console. Not the most convenient way for the users.

**Additional context**

This functionality already exists in the backend. You can add groups as blog post authors. The feature is just missing from the UI.

**Does this issue could impact on users private data?**

No

**Funded by**

Mainio Tech