Add a report button on the last activities page

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

On the last activities section in homepage and on the /last_activities page, users can have an overview on newly created contents (proposals, comments, meetings). Unfortunately, the content cards does not display the “Report flag” and the user has to open each content page.

**Describe the solution you'd like**

A reporting button would make it easier for moderators to fetch the last activities section and page and report content without having to navigate the platform.

**Describe alternatives you've considered**

Nope

**Additional context**

See https://meta.decidim.org/processes/roadmap/f/122/proposals/15627 **Does this issue could impact on users private data?** Ex. issues related with user's sign up/sign in process, verifications, invitations, sensitive data like email, IP addresses, etc. **Funded by** If funding is available, please indicate here which organization is funding it