Enable filtering reports by the theme (Thematic Censorship pages)

[majakomel]

On the new Thematic Censorship pages in Explorer we display reports from ooni.org based on the theme. We only show the last few reports on thematic pages and want to link back to ooni.org to see the whole report list, filtered by the theme.
On the website the reports are currently listed chronologically, without the possibility to filter them by the theme.

Todo:

• enable reports filtering by the theme
• update the reports page styling to be closer to how reports are displayed in Explorer
• update reports page to use Tailwind for styling components