add backloggd, hardcover and trakt website icons

[n1jos]

What does this PR change? What problem does it solve?
Added a social icon for the Backloggd game tracking, Hardcover book tracking and Trakt movie and tv tracking websites.

I received the icon from the official Discord server after requesting it in case of the Backloggd icon.

As for the Hardcover icon I also received permission on the official Discord server to use it. Though this time as png files that are offered on the official website. I then used a program to trace the bitmap and get the SVG icon from it.

For the Trakt icon I just took the SVG from their official website.

PR Checklist

• This change adds/updates translations and I have used the template present here.
• I have enabled maintainer edits for this PR.
• I have verified that the code works as described/as intended.
• This change adds a Social Icon which has a permissive license to use it.
• This change does not include any CDN resources/links.
• This change does not include any unrelated scripts such as bash and python scripts.
• This change updates the overridden internal templates from HUGO's repository.

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud