Allow RTE to comments

[aramollis]

Context & needs

Client want to be able to add format to comments (bold, linked text, headings... etc).
Actually you can only add links, mentions and quotes in comments. Very limited options. You can't add bolds, link with text, etc

Describe the solution you'd like

From the backend (as an admin):

1. You can allow RTE to comments in three versions: mini, full, markdown
2. You can restrict where this should happen (like you can do now with modify editors sections)

In the front (as regular user):
3. User could add format to their comments (bold, text links, embed video, ...) depending on the version of RTE is activated
4. If markdown is activated some kind of help text should be shown to help user to know the basic syntax

Describe alternatives you've considered

• We can limit the configurable options in (1) to few options (mini/markdown)

Additional context

• This feature is funded by Greenpeace ES and developed by Populate Tools
• In the future we are interested to allow attachments to comments (see Meta Decidim related issue #15810). Just to take in account.