Add a share button for bluesky

[newptcai]

What does this PR change? What problem does it solve?

I added a share icon for bluesky.
In my test it works for both light and dark mode.
The icon comes from https://simpleicons.org/?q=bluesky
I modified it so it is compatible with other share icons.
It has Creative Commons Zero v1.0 Universal (CC0 1.0) license.
So there's no problem using it.

Was the change discussed in an issue or in the Discussions before?

No.

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
1 New issue
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

[adityatelange]

Dup #1629