Added tags to all reports for Explorer Thematic Censorship Findings work

This PR adds tags to OONI reports (https://ooni.org/reports/) so that they can appear in the upcoming OONI Explorer thematic pages.

Specifically, I have made use of the following tags:

theme-human_rights
theme-social_media
theme-im
theme-circumvention
theme-news_media

Even though we don't currently aim to ship a thematic page for the "human rights" category, I have nonetheless added theme-human_rights tags to relevant reports (so that we can easily make use of them later). In doing so, I've included reports that cover a wide range of human rights issues, such as the blocking of LGBTQI, ethnic minority, religious, and reproductive rights websites.

It would be great if we could merge the reports tagged as theme-im and theme-social_media to include both under the new "Social Media" page.

Please note that I haven't added the above tags to the reports on the Explorer Findings page yet, as I'm waiting to hear back from the dev team when it's "safe" to do so (as they're working on some backend changes).

ooni / ooni.org

Added tags to all reports for Explorer Thematic Censorship Findings work #1609